First of all, you have to find yourself a truly reliable wallet.
For example Bittrex, Poloniex, Kraken, Bitfinex, Liqui, BTC-E, C-CEX, ETC
Hot storage or cold storage has its own advantages and disadvantages so depending on the requirements you can choose for yourself offline or online storage. However, keep in mind once again that only a small amount of Bitcoin on your wallet should be kept in your purse for the safest possible. Good luck.