My rookie tip: If you ever sell, don't sell it all, keep at least 10% of your corn for hodling.
I am thinking about a formula that aim to NOT sell more than 10% for every range - such as every 100% (or maybe less selling and a greater range?)
But it would go something like this:
Let's say that you started buying BTC at or near the top of the last bubble, but you stuck with it and you kept dollar cost averaging in. Accordingly, you have a average cost per BTC that is around $8k per BTC, and so you are a bit concerned about what to do.
You decide that you will sell no more than 10% of your stash for every time that the BTC price doubles (if it does)
Therefore, you have authorized yourself to sell 10% of your stash at any point of your own choosing at each point within the below prices ranges:
1) $10k to $20k (10% of total stash)
2) $20k to $40k (10% of total stash)
3) $40k to $80k (10% of total stash)
4) $80k to $160k (10% of total stash)
5) $160k to $320k (10% of total stash)
6) $320k to $640k (10% of total stash)
7) $640k to $1.2m (10% of total stash)

Etc. etc. etc
Exactly true 10% fact but long time holder can be possible profit 100% or higher oppose go back to see bitcoin up-down $3500-$4200 but next time was first move to $7000+ in the short time, in the better way to small profit randomly to possible higher profit if though possible exacly range point.