Find a website where there are many gamblers but not too many investors.

If tehre are very many investors compared to gamblers the profit will be low.

There are at least 4 websites other than just dice where you can invest in.

Satoshicarnaval [link] [thread] (Very new website, only 2 weeks old, looks very promising to me, low house edge of 0.48% so good for gamblers)
PRCdice / pocket rocket casino [link] [thread] (A dice site as well as a casino with poker and blackjack)
Dicenow [link] [thread](Biggest of these websites by far)
Everydice [link] [thread] (Just listed this for completion)