I bought a bunch BTC when it was $17000, then bought a bunch when it is $14000...then the price dropped until 2 days ago. I bought a bunch again when it was 6000ish...haha, now the price went up...so, really, when is it a good time to buy? When it dropped for a while and it rose a little bit, then drop again, then buy?
Most of people will try to help with their thoughts, but high are the chances that you won't learn from these thoughts. Your question basically asks about how to make money. Most of people won't say how to make it. You should search by yourself, studying some charts, techniques and the basics of trading ... It will help you. I personally would never reveal my trading technique because this could wipe out my edge over most of traders hahah... Best of luck for you!