When I first started out on Goozex, there were quite a few threads out there that were really helpful in getting up and running as a trader and making it a very positive experience. I hope LT continues to grow and get new people exposed to the joys of peer to peer trading sites like this and the crazy amounts of money you save while also being able to get too many games than you know what to do with.
So, I would like to share some things that I think would be helpful to pass on to others.
1 - Protect the games. When shipping a game, put a little piece of bubble wrap (or even cardboard) inside the case, on top of the game. This helps keep the game in place so it doesnt jostle loose during shipping and get scratched up or even broken somehow. When shipping a retro cartridge game, it is a good idea to sandwich the game between two pieces of cardboard for added protection and not a lot of added weight.
2 - Reuse, reuse, reuse. I save all mailers and bubble wrap I get that is in a usable form after I open it. I use bubble wrap often for reason #1 above, and reusing a mailer not only helps the planet a bit (thanks Earth!) but saves you some money in the long run. You will end up using an extra two or three strips of tape, but other than that it works just as well.
3 - Buy in bulk. A five pack of game size mailers is usually $5-$7 around me. But, I got a lot of 100 "generic" ones on eBay for $35 when I started using Goozex in 2008. Combining with reusing good mailers, I am still using that original set of mailers, though I am down to my last 10 or so. Same goes with tape; 1 roll of clear packing tape is about $3, but a 3-pack can usually be had for $5 or so.
4 - Ship early. Shipping stuff quicker just helps build the community in my opinion. I have been matched on a Monday night, and received a game on a Wednesday before, which is awesome. When the site works like a well oiled Amazon machine, it is fantastic for everyone.
5 - Leave feedback promptly, or let the seller know why you can't yet. Everyone wants their credits as soon as possible to get their next games, and appreciates things being closed out quickly.
That covers alot of it I think. If anyone else has other good tips they have realized over the course of using trading sites, please share!