How exactly does the money making process work? You buy some cryptocurrency for a certain price then sell it for a higher price and the difference is the money you've made? This would mean that the money you've made is still in terms of cryptocurrency. Then can that money be converted into the whatever kind of cash your country uses? How does it work?
Buy low, sell high. It means whenever there is a dip on the prices of your target coin, you buy it (wallet or exchanger) and wait for it to rise again to have your profit. You can withdraw a portion of your profit and convert it on fiat via some btc to local currency exchangers. Since everything depends on the country, I think it is for you to find out how to convert crypto currency to local money.