In this time i suggest you to invest your money on Ethereum or Bitcoin, because the price of ethereum and bitcoin is low right now and will grow in next month, but if you want get money profit you must hold it until 2020.
I agree with Bitcoin and Ethereum as they are the best coins in crypto market and considering that $500 is too small to buy more coins. But if you really want to diversify more then maybe $100 each coins but you should be extra careful in your research to avoid losses.
it is better to be safe especially when investing even it is a small amount of money it is better to go with eth and bitcoin do not settle for an investment with alts because it will really took so much time for your investment to have a good profit and since the market is too cheap it is better to buy more and more and keep holding those coins because it will really benefit you in the end of the day,