As a long-term holder, I just HODL. That saves me a lot of headaches and a lot of trading commissions. You just put an example of what newbies do: to buy after the last ath out of FOMO and to sell after the dip out of panic. This is the opposite of what I usually recommend
My style exactly. I don't want to be associated with all that daily drama of day trading.
In hindsight, I can say that holding coins and not dealing with all that minor price fluctuation is far better if you have a normal job and don't have time to react accordingly to ever-changing trading patterns.
I recommend only to sell, buy at major breaking points - ATH is a great time to sell and crashes and corrections are great entry points.