The simple rule is "buy at the bottom and sell at the top". But i don't think this applies to all coins, it only applies to solid coins like bitcoin, ethereum and the likes, because they have stood the test of time and would surely find their way back up. But most of these new coins, if you buy at the bottom, the price might still go lower and keep you trapped there. so it is better to wait and see a clear move up before you get on the train to avoid fake outs.
Yes, certain strategies only applies to solid project otherwise if you apply this to shit coins you will definitely get rekt in the process, it is better to watch that new coin closely for sometime and see the market behavior before you can decide, especially when the team are actively developing the project, most new project don't worth the trouble, the developers are also short-term seekers so once they hit their target they stop developing and that will be the end of that project.