One of my learnings from past months has been that even if diversifying is a must, you should work out a strategy across different coints - but never exceeding 5-10 coins max.
This depends, of course, on your free time and budget, but if you want to maximize the investment outcome you really should keep a close monitoring and eye on the progress and news. Therefeore being present in lots of coins is just not doable, as at least some of them will probably go up and down, without you having even noticed.
My recommendation is to have more focus on less coins: What happened to me earlier was I had 30-60USD in 20+ coins.. When one increased 20% I wasn't actually doing more than 6-12 USD... Therefore my strategy is based now on having at least 200USD+ in <5 coins. This way you can better feel your gains into your pocket, while you can limit any negative dip by using the stop-loss.
Now it is easier to follow up with news, set orders in advance and anticipate to the market, which is ultimately the main goal if we want to make money.
What are your learnings??? Look forward to hear your mistakes that might be helpful for novices..