1). Check the BOI, and try to find reviews of the seller. If needed, post an inquiry thread on the BOI.

2). Ask about guarantees. What their terms of service are. What protocols they take if an animal arrives DOA, missexed, sick, etc.

3). Ask for a picture of the snake on the scale. I've seen a lot of people get ripped off on weight.

4). If paying through PayPal, use a credit card. It's easier to dispute with a credit card if something was to go wrong.

5). Ask what the snake is eating, how often, and if feeding charts will be provided.

I can't think of anything else right now. I've never bought online yet.