ask a LOT of questions about the cue, offer a LOT of details about your cue. Communication is the most important. Exchange a lot of clear, good pics,
and lastly, do a search on the person you are about to deal with...if nothing bad comes up, and they have a good established itrader, and previous posts on items for sale, they have reputable members vouching for them...
then you are probably pretty safe.
Ask about a return policy, many members here will give you a 3 day or so if not happy...but then its only fair that you extend the same courtesy to them if they arent happy with your cue.
There are some GREAT PEOPLE on here that I would trust completely, but also SH!t happens-so take the usual precautions. Escrow is safest, just sucks to wait longer...I know.
Go with your gut, and talk to the seller by phone-many times you can feel them out by voice somewhat, in the end, if u dont escrow, youre taking a chance.