1. !Most important thing is, to watch the action on the dohyo.! (too bad juryo-stream is gone)
-Follow the news. (sumo-now.com, or sumotalk.com. banzuke.com mailinglist...)
2. Bet only on those, that you really like. (at least I feel rather bad when I bet against my personal favorites)
3. Go with your gut-feeling and regard the posts of the forums (sumoforum.com, http://tipspiel.sumofan.net, info-sumo.com...)
And at last, the key to winning something, is to get the perfect mix out of your own feeling and the actual records of the rikishis.
(I apologize for my all too bad english)
ect. anybody else got the feeling juryo is close to lotto (and i don't mean lotto baggins)