The best way to increase your Bitcoins is to trade at Poloniex, Kraken, etc.
It is just like the Stock market, like if you believe that price of Ethereum can rise by 10% in next 1 week, buy and sell it, and increase your Bitcoins by 10%. It’s as simple as that, but do proper research and reasoning before you trade.
Here is an example, I got 200 INR of free Bitcoins using a Coupon code at Unocoin. I transferred 0.0008 BTC to Poloniex, and after trading dozens of times, 0.0008 BTC turned into 0.0120 BTC. At that time I invested in Ripple and it’s price risen to around 12 times, and once its price started dropping I sold it. I did some other trades with less common coins too. Even losses in some trade, but not much as I always use Stop-Loss ( Stop-Limit).
I believe in Value Investing, but since that BTC was free. So, I did trading without the fear of losing it.