Here is small tutorial how to make free skins:
1) go on this site
2) get your 500 free coins (worth 0,5 dollars) using STEAMFREE code
3) deposit some skins (you will have bigger bank = bigger profit with less chance to lose)
The site is about rulet. You can bet on three colours - red, black and green (14x your bet). Basicely it's just about red and black betting. If you bet on the right colour, your coins are doubled.
You can maximalize your chance of constant winning with simple tactic. You start every round with 10 coins bet (for example on red). If you win you repeat. If you lost you will simply bet 20 coins. In the end you will win again 10 coins.
It goes like that: 10-20-40-80-160-320-640
I have made this skin just in 5 minutes:
Good luck :)