Buy low, sell high.
That's the strategy for any sort of trading not only bitcoin. With bitcoin long term study of the price variation is required so to have exact predictions on buying and selling because none knows exactly when price increases and decreases like other currencies as it wont depend much on world economy.
and also difficult to buy low and sell high in bitcoin trading, sometimes very long stable prices.
but it was very well done in trade altcoin. You can take short-term daily