Look at the market at the moment! Many coins of the promising ICO are now traded at the price of ICO and even lower, so choose the most promising project for yourself and invest in it, and when the market starts its growth you will be able to increase your capital. If you don't want to go this way, you can only trade on the exchange
I don't think any coin will accomplish what bitcoin has done.
I think stories to get rich with 50$ investment are ferry tales, we are not in 2009 any more and there are some coins that increased their value multiple times such as eth, dash, litecoin but I honestly think these days are over. We might see some coin increase 10 times over few years but I believe we won't see 100X or 1000X any more.