With only 500 dollars you cannot really invest in the top coins in the market because even if those coins are going to give good profits in the future you have to wait a lot of time to get very small profits, so the only thing that you can do is to invest in coins with very low market caps and hope that the coin in which you invested your money goes up significantly, even if the coin we are talking about goes up 100 times in value you will only get 50000 dollars.