Make sure payment is genuine. Bank deposit slips/ Proof of internet payment can be faked.
Have the buyer complete 3 (not 2) transfer forms. Hand one in yourself, and get a receipt. Keep the 3rd as spare in case the lisencing office chucks the copy you handed them in file 13....
Keep a copy of his ID
As long as there is no transfer form handed in, you stay responsible for the fines.
Ensure you make them sign they are buying the car as is from the day you hand over the keys...
I have had many ppl try rip me off (EG, i pulled out my car sound before selling, i told the guys i was, i made them sign that the car was as is when they drove it off....got a lawyers letter saying they demand sound or cash to the value of xxxxxx/thumb sucked amount..... i lol'd)
make sure your insurance covers them when they test drive, I have made previous test buyers sign forms stating they are liable for the excess should they have an accident when test driving the car....