I greatly prefer trading over buying or selling.
Systems that I own that I might want games for include Atari 2600, NES, SNES, Genesis, Saturn, PSX, N64, Dreamcast, PS2, GameCube, GBA/GBC/GB, Nintendo DS, XBox 360, and Wii. So if you want something from my available list and have games for those systems, make me an offer. It couldn't hurt to try.
I prefer ALL games to have a box and manual, even ones that I listed as "don't care." Any game that has a box and/or manual will be worth more to me than the same game without it.
I don't like sending first, but if I have to I will, given the trader has more completed trades than me and all "excellent" rating averages.