I would recommend to invest in a coin that is not even on the Coinmarketcap, because the amount is very small, in order to expect a big profits by investing in large coins.

If i had 50$ for investing, i would prefer to unvest in some HYIP project and get a chance for fast XX. This is a reasonable risk considering the sum

If I only had $50, I will not invest it in any coin. I will research a good ICO with minimum investment around $50 and have it there or contribute my money  together with a friend for an ICO. If You can increase Your portfolio value to $250 , You can have good trading decisions and start a good journey from there.

Choose a coin that is so cheap, there area  lot of cheap coins right now and you have to do your research about the potential of the project.
With a small amount of money as your investment, it's wise to take a higher risk so you can grow your money instantly.

To get the most profit from investments, you need to invest in ICO. Other options to make x4-X10 for a couple of months I do not see. For example: yesterday I invested in  Llitenett project , let's see what will come out of it after the end of ICO. Invested only 60$.

I would invest that 50 into Verge (XVG) based on the news that Pornhub is now integrating it as a subscription payment option.
More info http://technewsleader.com/2018/05/05/after-pornhub-verge-xvg-partners-with-trafficjunky/.

LOL, Verge is much more overvalued! No-one pays for porn and I don't think they will get more volume or a price increase, if the hype goes down the price will fall very much!

Pundix Pundix all the way :-)

I will personally invest in ETH even if I have more than this. I believe there is a very good future for this, looking closely at the occurrence in the past weeks and looking back to when this token all started out as a minor token and getting to the stage if becoming the number 2 token in the cryptocurrency world behind bitcoin so u believe it has a very good future and tendency if increasing mire than imagination.