The above mentioned idea is a good one, however if you don't have a friend who owns this game or you want to challenge yourself, there is a decent way to do it.
There is a lobby system in which you can join other players and send challenges. You also get the benefit of seeing their win/loss record and the game gets you an odds of winning percentage.
Scroll through the list and find someone who has a bad record or around a .500 winning percentage and send a challenge. Be cautious though, look at their latency. I had someone with one red bar and 3-4 times during the match there was a 4-5 second pause, it can really mess up your timing for moves and blocks!