The best strategy is still to dollar cost average in.  And don't forget to diversify.  Long term, Bitcoin is still going to be a good buy, at least a better place to hold your wealth than say the fiat money.  Don't be scared by these short term price fluctuations... it's all noise.  Crypto is still a great place to be, just put in little by little and 16 months from now you won't be sitting on the sidelines wondering if you should buy-in.