@(you need an account to see links) It's really fun, in my opinion. You have to have people that know what they're doing. Bans are kind of crucial. Tanky DPS + Burst champions are the best choice, not so much poke comps.
Land your poros, really.
It's just a matter of team synergy I guess. If your team just picks whatever they want to play without really thinking it through, chances are you wont win often.
But sometimes I go through massive stomp phases where I get crushed about 5 games in a row, then win a lot. Right now my match history is 8 win 2 losses so im not complaining xD