Playing it more is definitely the way to go. A few guys have made guides, but the pace of development has been phenomenal, which has left most guides outdated reasonably quickly.
The "How to play" section is probably best. Learn about the different abilities; and put your monsters to work. Try and predict the outcome of each match before you hit 'Rumble'. Then watch the match.
If it doesn't end the way you thought it would, watch it again to work out why. Best way to learn.