internet scams how to avoid??

As Pateras said be cautious of the over payment scam and keep in mind that certified checks and cashiers checks can be phony too. An example is : I was selling a BSA motorcycle and we agreed over the phone on a price,a date of pickup and an assistant was to transport. Long story short, certified check came with over payment (secretary made a mistake) just go ahead and deposit and give the overage to his pickup guy (after taking out $100 for my troubles). The pickup guy showed up a week early insisting on getting the bike and title and the extra money. After punching him out and threatening to call the police he left and never heard from them again and of course the check was bogus.