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?
I am a short term trader so I suggest to look at those coins that has an upcoming events because news has a huge influence when it comes to price in crypto. Besides, these are the coins that has a high tendency of being shilled by the people may it be in reddit, twitter or telegram because they have a reason why someone should buy that coin. Take a look at https://coinmarketcal.com/. It is cryptocurrency calendar and you can contribute in there too if you know an important event of a certain coin. I also use https://cryptostat.org/. It is a site wherein the volume and prices of the coins are track in different time frames so you can see the percentage changes which is a big help when you are looking for a coin that has a big change in price or volume. It is paid though. If you want to know about some ICOs, try https://icobench.com/. They also review an ICO which you would like them to review for a fee.
That's a lot of site that I'm not even aware of. The only reliable source I knew was coinmarketcap.com and no one else. Since most of the coins created are included in the list.