For dragonboat, the season just ended, but you can look on
http://www.dragonboatwest.net/ in Jan to March and teams will be recruiting by then. There's also a ton of info so you can learn about it first and of course there is the gigantic dragonboat thread here in this forum
For the other sports, I'm sure there are similar websites for respective leagues with teams looking for players. I know the volleyball season just started.