Always buy some coin after a big price drop. Then sell the majority of that coin when the price returns to normal, and move the remainder to a holding account.
Also, you could try to sell at the top of spikes and buy back after the correction. That's much more difficult to pull off though.
This is probably the best adivce.
After a steep drop, there is almost always a correction back up, to about 50-80% of the price before the drop. If you watch closesly, or set alerts, you could profit of this.
Yes, maybe only this! But this doesn't work all the time as well. After a big drop, you might have a second wave and even bigger second drop.
All in all OP, it's a gamble! A pure gamble! As one of my friends has suggested, I prefer betting on sports instead. With sports betting, you at least have odds in the beginning and you can have some insight on what might happen. With Bitcoin trading, you know absolutely nothing!