Is it a goog idea (when you think in terms of profit) to buy a coin when the percentage shows for example -5% and then sell when the percentage shows +5%?
No, because you are not 100% sure if that coin is going to recover in the next 24 hours, maybe you think that those prices are a good signal to buy, but they are not.
And that % is the change in the last 24 hours.
Just buy those who have the most volume, because they can give you a lot of succesfull orders of 1% - 2% easily.