I was in your shoes, I would win a lot, build a big account and then make a huge bet that I thought was a sure thing and lose it all. What I do now is keep my bets pretty much equal. I dont bet more than 10% of my account on one bet, no matter how much I think its a lock, because there is no such thing as a lock.
So if my account is $1,000, I will bet around $50 on a game. If I feel very strongly, then $100, but no more than that. Lately I win more than I lose, so I am consistently making money now. So if you win more than you lose, this should work for you. I believe if you ask any successful gambler, money management is the one thing that all will agree with.