If I have more trades than you, then you send first.
If you have more trades than me, I'll send first.
If you got a bad trader rating, you have to send first.
I think a lot of people are too interested in getting the better deal instead of realizing they're trading to get games they want to play and giving a fellow gamer games they can play, and very cheaply at the same time. If you look at my list of completed trades, you'll see that I usually get less than I give, and that's mostly because I acknowledge how much I'm saving by trading, and because I'd much rather have a game that I can play than a game that will sit on my shelf collecting dust, regardless of how much it's worth.
I am currently living in Italy until may, so please understand if I don't respond, once I get back I'll be able to make trades once again, but if your looking for something and want to trade in the future, I may be interested, so don't hesitate to offer in that case