There are many ways to grow your Bitcoin but i think the best way is trading and investing.
Trading is the best way to grow your bitcoin but in the first place you need to ask yourself if you are ready of doing so. There are a lot of traders now and even those new investors are taking up the risk and they are buying their own alt coins and choosing it for their own portfolio. You buy low and sell it on high prices, just repeat the steps and you'll grow your bitcoin in due time.
Trading can easily help your grow your bitcoins if you will be a day trader, you can take advantage on the price volatility
if you have the knowledge that will help you to make a good timing to buy and sell, it's easy for you if you will become consistent, it's a long journey so you have to learn from your mistakes all the time.