got scammed what to do

go report them on steamrep

nothing never wish what was the deal with him the only way was to use next time the trade function on steam

Why did you go first for a game key?

If you are trading keys for tradeables/gifts, you may go first with the key, but you should always check his steam rep, steamtrades profile, steam profile (You shouldn't pay that much attention to his profile, since it's easy to farm rep there). Not sure if you will be able to get your things back, sorry mate.

You'll learn. Everyone has been on this boat at the beginning

Hint to steam guys - make an option to check when the key was reedemeed. I know it wont work from the first keys.

But it would cut the scammers who takes the keys and says that they are taken, and they use them on other account or retrade.

Dont know is it a simple thing to do, but lot of scamming would be gone.

Whats the best way of trading is the Steam Trading itself , giving items for a game inside the trade , no trust needed ( Ex. in case i explained this somehow weird http://puu.sh/39Fwh.jpg ) However if its a game with a cd key , its a huge risk .
Usually when i do these kinds of trades , i check steamrep first to see if hes trusted , then i might go first or if hes neutral or a scammer , i will ALWAYS go first , no matter how much i want the game .

QQ, that what you can do, then learn from it