If you do not wish to take big risk then stick with the top 5 to 10 coins. Invest in them and forget about it. Come back to see them after 1 year and see how they are doing.
I am sure out 10 coins, at least 8 coins would get delisted from exchanges. In never accept any recommendations to go for investing with altcoins. They are highly in stable compared to bitcoin because fundamentally altcoins are not having any strong bases to sustain for long years. That is the reason utter jokes had become hit and many good concept based coins were gone away in months.
For $500 or even for lesser to that amount, bitcoins must be the right option to get into cryptos world of investments.