Very polite and helpful. Especially good since they helped me on my first time trading.
Trade#1 Gone Home With Soundtrack for Human Resource Machine.
Trade#2 RAGE for Dear Esther and Aqua Kitty: Milk Mine Defender.
User left the link in chat when around after I made sure the trade was still okay and then I sent the link when I was around. Straighforward, trusting and simple.