I am a little bit confused, are you asking about trading coins or good alts for investment?  Both are different for me. There is no longer trading, it's hodl! For hodl purpose, after Bitcoin, you should pick the top coins like ETH, LTC, EOS, BNB, LINK, ATOM and so on! Because there is less risk. But yet you should research yourself before investing in any coins, don't follow someone's prediction, strategy, make your own!