there are so many cryptos and I find it hard to identify the ones where I should have a closer look.
Obviously one can find cryptos e.g. by listening to shilling on Reddit. But I'm looking for more professional sources like YouTube channels, free/ paid Telegram/Discord groups and so on. What do you use?
Those paid memberships of exclusive groups are definitely more reliable than those that you can freely read and browse over the internet. Expect the most of what you can freely access in the internet to be lopsided. The premium groups are made of experts. The ones on free groups are made up of just anyone who wants to promote the coin they are holding.