That's the key there. The simplest (and one of the best) methods is the % staking plan everyone is spruiking. However you need to pick the actual start % yourself based on a few things - strike rate, average win, your risk vs reward motivation etc.

If you have a high strike rate (like Chromes 70% above) then using 0.5% is way too "safe". However if you have a long-shot theory than 0.5% could be quite valid.

One thing I also like to do is define reduction levels to build some protection into the profits. Eg. if I start betting 3% of $500 I may choose to reduce the stake by 0.1% everytime my bank moves up by 500.It ends up with something like this....

Bank and %
500 - 3%
1000 - 2.9%
1500 - 2.8%
2000 - 2.7%
2500 - 2.6%
3000 - 2.5%
etc

All the way down to whatever level you feel comfortable at. Some punters dont like this and I certainly dont use it for every system, but it does offer some "protection" for your profits against the expected long run of losers and still builds the bank nicely when performing well.