For exchange, I will suggest to you the best global exchange, Binance. It has lower fees and you can find out so many coins or tokens there. This is also trusted and has a very great reputation.
But if there is a trusted and reputable exchange local in your country, you may also consider it.
For coins that you want to pick, please consider what kind of investment do you want?
if you want a long-term investment, just go to Bitcoin.
But if you want short-term, I suggest you buy Ethereum, BNB, ADA, DOT.
Moreover, right now, the price still dips.