One of the most important factor of a successful gambler is to know when to stop, most gamblers expecially the addictive type don't even know what is stop when it comes to gambling. So it's very important to;
* Stop when your losing is now getting to you.
* Stop when you are now feeling as is you can't do without gambling.
* Stop when you have a big winning, by channeling the money somewhere else so you won't lose it back to gambling.
* Stop when you are not even winning at all, it's not your thing.
* When your losing is weighing you down, stop and restrategize .
To be honest, the best way to know that you need to stop is to search in you.
If you feel like you lost too much, stop.
If you feel like you gambled too much, stop.
If you feel like you spent too much time gambling, stop.
Etc...
At the end of the day, you need to be in control of your life.