I think that you should quit when you are 2X what you started with. Now that's very hard considering that most ppl start with very little. I deposited with 10 dollars and intantly brought it up to 130. I decided that i wanted to cash out and was proud of myself. But most poker channels have a raked hand policy that doesn't allow you to cash out. So, when i cashed out they rejected it saying that i needed to play more before i could cash out. Therefore i did i made my way up to $300. I then lost 60 to $240.
You start to get careless at this stage. I think the best thing to do is to take a brake and relax, come back in a day and play again with a clear mind to further building your roll.
Anyways i wanted to get that 60 bucks back fast and sat down at the $5 no limit table. I lost the $240 in about 5 hours. i went all in with AK against a bully stack hoping that he would call because i reraised him and he ended up having AA. My roll is gone and i'm bitter.
The name of the game is patience. Play the high limit table if you have the roll. You can have hope to build up your money. Patience is everything, only play prime hands and bet the pot don;t play around and go all in. There is the chance that you will get callers and possible lose your roll.