If you are new in the cryptocurrency market then first I recommend joining this forum, you will be more experienced and get more useful tips. Then you should learn about altcoin or ICO that you want to invest. You should invest in potential and valuable altcoins, because in the future the cryptocurrency market will grow sharply and the altcoin price will be very high. However with $ 50 it is hard for you to buy good altcoin, so You should choose a good ICO project to invest.