20$ worth of bitcoin may not be that much, but if you are smart enough and willing to take risks you can maximize it and make your money grow. If you want to earn profit asap, trading is the way to go. You can buy and sell coins within the day and get a profit out of it. If you want just want it as an investment, just leave your money in bitcoin. Sell it when you think you earned enough profit already then buy again when btc's price is lower. I'm not suggesting gambling but it can also help you earn more btc but at the same time, you can also lose your money there.