i will not encourage you to invest your money on alt under 20   cuz it have a high risk although u have a small amount of money(500)
in my opinion pick up 3 or 4 coin from the first 20 coin and do ur search about them
if u ask me about my opinion i'll make an advice for u and i'm telling u to invest ur moeny in (cardano,IOTA,and ETH) i belive that those coin have a grt future cuz of the power of their technology that they come to us