Is it once you make a certain % profit? Or is it if you need the money? How do you feel about the fees? So on.
I set the target at the time i bought the coin/token, so when it reach the target price i will sell half of it and keep the rest until i am satisfied with the price. You should invest the money you can afford to lose and you should save your money every month so when you need money you have savings account that you can use, not your investment. The fee is not high, i considered it small so it's not a problem.
I like this approach too. It's also what people who are in the stock market advice to newbies. Having a target price, say 2x, ensures you have locked in a certain amount of profit. Allocate half of your tokens for that. Cash out when you reach the target price. The remaining coins or tokens, you can play or hold longer.