Bitcoin is very volatile. So, you better buy some other coin. But, If you want to buy Bitcoin, you have to buy at day lows and sell when price is up. Now, this strategy is difficult for Bitcoin is up and down fast, in the same day. You can also buy for a long period. It would be dangerous.
Bitcoin is very volatile and most of the other crypto currencies are also so better invest on bitcoin long term because these volatility is just temporary.My strategy on bitcoin is just buy at the current price and hold it for some years like five years then we can know the real profits from investing on bitcoin.