Looking for some Advices

Hi everyone! I recently turned 18 last month and I’ve been thinking about what to do with the cryptocurrencies I own.
I started investing when I was 15 and bought some Bitcoin, which is now worth around €1,1k. I also hold some Litecoin. Now I’m wondering: should I sell everything and cash out, or would it be smarter to hold for a while longer? And if waiting is the best option, how do I know when the right time to sell is? I’d also appreciate suggestions on which cryptocurrencies might be worth exploring and what resources (videos, books, courses...) I could study to better understand the market.
Thanks a lot in advance!