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. 
I think your idea is very good but to be able to trading you must have very sure knowledge, accurate information and always updated information. You also need to experience the most important thing. This is a very new market and there are many risks so if you do not understand clearly you will lose money.