That's when you have most of your issues, is during your first transaction(s). It takes awhile to learn how to avoid issues but you sort of learn how to avoid most trouble. Here are some things I have learned and do.

1. If it is expensive, i contact the seller with tons of questions to get an idea how they respond and how reputable. The faster and more accurate the responses, the better i feel and vice versa. If they can't spell, for example I am concerned.

2. Scour the feedback. Look up and down, sideways and back. Look for patterns etc.

3. Look at the general listing. You can somewhat tell if you are dealing with a moron in a lot of cases. If they make outrageous statements in the listing for example. Or have horrible grammar and lots of spelling errors. That tells you that they might not be very conscientious.

4. Look for nice pictures. I never buy crap i can't see clearly. This to me is another sign of a slob. Not careful enough to take good pics is a negative to me.