1. Check my sig and sign up there yourself to make it easier for people to view your cars.
2: Let people know what you want. This will cut down the time it takes to make a trade and prevent long winded guessing games.
It's incredibly irritating when guys just say 'I have an X1, what you got?' or 'Make offers'.
3: Back up your gamesave before you trade to prevent any possible losses. If you're not sure how to do this, search the forum.
4: Be clear about when you can trade/send a car.