that itself will take you a lot of time and effort to figure out. Once you do, you have arrived. For starters read the stop loss thread in this forum, but dont agree with all of it!
Why don't you allow a computer to give the result out instead?
There's a trade off between bet size,long run profit stats and drawdowns. If you have a strategy in place, I guess you can experiment with the risk exposure to reach some reasonable conclusion about the possible size of bet...