Trading is a good way. Setup an account on an exchange and buy a little of a cryptocurrency you are interested in. Study the charts and try to buy in a dip of a popular coin. Once you bought a coin, set a sell price a bit higher enough to offset your trading fees and to make a small profit. Rinse and repeat until you grow your stack. Just remember to buy low and sell high. 
Aside from trading . You can also try in joining a signiture campign. It was more safer than doing trading. Because you cannot control the price of bitcoin, sometime it really fall down , and sometime it rises. It happen that when the bitcoin price fall down many of the holder panic to sell it. They doesnt know that it is just part of the fast growing improvement of bitcoin.