More involved version for people with an adult's attention span:
A) This all takes some work, but if you want a person you've never met to come and give you thousands of dollars, then you need to put some effort in.
There's lots and lots of cars for sale - if you make life difficult for a potential buyer, then chances are they will steer away from you, and buy someone else's car.
A good ad gives potential buyers a good idea of the car before they've looked at it, so the buyer can make an informed decision whether to contact you or not.
Never mistake asking basic questions for genuine interest. A crap ad might get 20 people asking you questions, misleading you into thinking that lots of people are interested. A decent ad might only have two people contact you, but they are people who are genuinely interested - and they are far more valuable to you!
B) Choose where to advertise.
Facebook Marketplace and Gumtree are no-brainers because they're free and widely available, but do have a higher ratio of time wasters and dreamers. Carsales is good for more expensive cars (I'd say $5000 at a minimum), but probably as waste of money for cheapies. Ebay is pretty terrible nowdays, but can be good if you're really desperate to get rid of something.
Enthusiast forums and FB pages are excellent places to advertise, especially for older/rarer/interesting cars.
C) Put a clear title on the ad, that can be searched. If you have a useless title like "Car for sale", then nobody searching for a particular car will find your ad.
If you say "2002 Volvo V70R, auto" then you have a bunch of key words that allow search engines to work, and you've answered most of the basic questions straight away.
Also make sure that you fill out the correct check boxes too - a perfect car ad that's buried in "Baby equipment" will be hidden from almost everyone. Similarly, ticking "manual transmission" when it is an automatic will mean everyone looking for an auto won't see your ad - and almost everyone who does see it will be annoyed when they realise it isn't the manual they're looking for... Get the details right, because the internet is very literal.
D) Write a clear description. Type it out once and it's done - if you think you're clever by asking people to message you for details, then you'll have to type it all out a dozen times. DO NOT mistake people asking for the basic details as real interest. They're just trying to get the info you should have included.
At a minimum, your clear description MUST include whether it is an auto or manual, how many kays it has travelled, how much rego it has, any significant faults.
It is also helpful to mention any major work that has been done recently ("tyres are 5,000km old" for example), any ownership history that you know, and any extras (towbar, sunroof, whatever).
Be honest. If you 'forget' to mention a loud rattle in the motor, then you're wasting everyone's time when the potential buyer comes over.
Don't try to be funny. For every viral ad you've seen, there's dozens of people who have written a crappy ad because they forgot all the details while trying to be amusing.
You don't need amazing English skills, but if you struggle with spelling and basic punctuation, then get someone to edit your ad before you post it. Similarly, ALL CAPITALS IS A BAD IDEA BECAUSE EVERYONE THINKS YOU ARE SHOUTING.
Do NOT keyword bomb (where you add a bunch of words to your ad so itappears in more people’s search results). It doesn’t work, and annoys the crap out of people.
E) Photos!
Wash the car and vacuum the interior, let it dry and then take the car somewhere with some space around it, and take lots of photos. If they're blurry or too dark, then ditch them and take the photo again. Move around - don't take five almost identical photos.
I would strongly recommend these as the MINIMUM:
Front quarter view of the whole car;
Rear quarter view from the diagonally opposite corner;
Engine bay photo - the less you know about what everything under there is, the more important this photo is;
The interior from the open driver's door, showing the dash, front seats and the pedals/gear lever;
The back seat;
The badge(s) typically below the tail-light/on the bootlid;
Any significant dents, scrapes or rust.
The instrument cluster, showing the odometer and any warning lights (or the lack of them!).
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When you upload the photos, make sure that one of the exterior photos comes up first.
Don't post more than one "arty" shot. I know it looks cool covered in foam, and the paint looks awesome when it is wet, but these photos actually aren't helpful for a potential buyer. Similarly, a maximum of one action shot - even (especially!) for motorsport cars.
Any modified car should include photos of the modifications. If it is a race car then clear photos of the rollcage and seats are super important.
Don't bother blurring the numberplate - the plates are visible every single time you drive the car, so you're not achieving anything by blurring the plates. The only exception to this, is if the car has modifications that are not legal/approved/engineered.
F) Price.
Number one: Put a price on it! I know you want people to offer you mega dollars, but it isn't going to happen. You know what you'd be happy with - save everyone a bunch of time and effort and put a price on it. It's OK to say "negotiable" or "or near offer", but not giving people a starting price massively reduces your chances of making a sale.
Number two: Choose your price. Have a look at the price of other, similar cars that are advertised, and have a look at how old the ads are.
The best way to do this is to watch/save/follow those ads, and see which ones disappear and which ones stay - if they're all sitting around without selling, then you know there's no market at that asking price, and you have to go lower.
Once you've decided on a price, then imagine you're a buyer looking to buy a car similar to the one you're selling - if your car isn't the first or second car you'd inquire about, then it is priced too high, simple as that.
Be realistic about the value of any modifications or features! Being one of 80 red manual 1998 models doesn't make your one worth any more. Similarly, a set of $600 Chinese wheels have probably devalued it...
Any faults that must be fixed, will devalue the car by about double the cost of fixing the fault. Often the maths won't work for you... Sorry, but that's reality.
G) Dealing with stupid people.
Yes, people suck, but if you are grumpy and difficult to deal with then everyone will be a problem. In other words, you catch more bees with honey than vinegar...
So you've got to expect a degree of stupidity, even if it means gritting your teeth and not abusing them for being morons - be polite and answer their first round of questions at least. If they keep asking dumb stuff, then redirect them back to the ad (because you've got a good ad that answers those questions). If they still keep pushing then you're probably right to start ignoring them.
People who are genuinely interested have/will read the ad properly and any questions will be confirming what's in the ad, or digging deeper - don't get the poops with these people because they're your best bet for making a sale.
People who phone you are far more likely to be serious than those who text. Those who text are more likely to be serious than those who message you - but don't disregard anyone who is communicating like a human regardless of the method of communication.
H) Not getting ripped off.
This section could be an article all by itself, but here's some starting points.
Yes there are scammers out there. But if you assume everyone is out to scam you, then you will make your own life much harder. Keep in mind that not many people are out to commit the crime of the century by scamming you out of your 2006 Barina...
If someone rings you from a non-private number and identifies themself, then that's a very good start. If you're worried, then google their name and/or phone number - if their story matches what you find, then it is less likely they're a rip-off artist. Talking on the phone makes a person real - it gives you a much better feel for the person, and it makes you a human in their minds.
Ideally, text your address rather than Messenger/Gumtree messsages - a phone number is a better link to a person than a FB or Gumtree profile.
If the car is valuable or particularly desirable, then it is always a good idea to meet them somewhere public when they come to look at your car. Maccas and service stations are good because they've got cameras everywhere and are generally tolerant of people hanging around.
Trust your gut. The vast majority of people are terrible at lying, and those that are good at it generally aren't pulling used car scams - they've moved onto more profitable ventures, like politics.
I) Haggling.
Everyone loves to haggle. Don't bother with being offended by any offer. Just say No, even to the stupid ones.
Remember that they are offering you money to take away the thing you want to get rid of - seems pretty crazy to get angry at someone who is offering you money... Save your sharp words for the people who are actual dicks and try to talk shit. As a buyer, I try to avoid saying "its a POS, it's only worth a quarter of what you're asking" (even when it is what I'm thinking....). Instead, I say things like "To me, it is worth $X. I understand you want more, but it is a genuine offer and I can get you the cash in the next ten minutes", which is hard for people to get upset about.
If you think there's a chance of making a deal, then come back with a counter offer - they've started the dialogue, if you want to make a sale, then it is up to you to continue it.
The sellers who are driven by ego are the easiest to haggle down, usually because they've burned off every other potential buyer and end up desperate.
Think ahead - if the ad has been up for two months and the only person who has contacted you is standing in front of you with cash in their hand, then decide if you want to burn them off in an attempt to make another couple of hundred dollars.
J) Sealing the deal.
If they give you a deposit, then write a receipt clearly stating the amount of the deposit and how much is still owing on the car. Include the rego number and body number. Specify a time for the rest of the money to be paid (two weeks is normal) and that if they balance isn't paid in that time, then you get to keep the deposit and sell the car to someone else. Make two copies, and make sure they sign your copy.
Count the money in front of them. Keep the Notice of Disposal and hand it in. Check their licence and make sure it is the same person. Don't ever give them the car on the promise of the final payment being made next week.
Old rego papers can be signed over just like current ones. If you don't have any rego papers, then write a receipt that clearly identifies the car, the date, the seller (you!) and the buyer. Also mention the sale price, and that it has been paid in full.
Then go an find all your ads and mark them sold!
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This is my experience from buying about 250 cars over the last 25 years. Your mileage may vary, but trust me on how asking for offers is a terrible way to sell stuff.