First and foremost, when the time comes take some fucking profits.
This is what I must regret.
If I had take 10-20% profil I would had recover almost all my investment and would be relaxed now. Possible buying more.
Looking back that's what I'd most definitely do - sell all @20k and rebuy at 3k (all in)

Unfortunately (or luckily) I'm not a trader but a HODLer.