I'd suggest looking at a site like coin market cap and only investing in the top few (5-10) coins by market cap if you wanted to diversify.
Investing in one of the top 10 coins is the safest investment but you shouldn't expect a big profit from it in a short time especially when investing a small amount of money (no offense @OP).I'd rather suggest using those 500€ in day trading. It's not as safe as investing in top 10 coins but with good management and the right skills, you can make a good profit out of it. no risk, no reward
