DCA (Dollar Cost Average)
It's simple and not complicated  all you just have to do is pick an amount you can afford to invest in a specific interval( depends on you), you must be willing to  do it consistently  and hold for a very long period (this is very important) . The purpose is just to spread your entries and could worth it than just waiting to buy when the price falls . No one can assure you the price will fall but if it does you have  opportunity to buy low as well and if it doesn't,   you already have an additional advantage and you'v yourself for the up  .
Once again, if you are after the short term profit you might end up selling in loss when the price falls