Every year during tax season I regret it: why didn't I honestly keep records back then... Now my simple method is: export from the exchange once a week, for on-chain transfers just quickly jot down txhash, time, counterparty address, notes into a spreadsheet, and keep a screenshot (don’t find it troublesome, it really saves your life at year-end). Also, for airdrops or staking income, don’t just note "received," it’s better to clarify roughly how it came about at the time, or else you'll forget in a few months.

Someone asked: Isn’t there an on-chain data tool that can automatically tag things?
Yes, but it’s lagging and can be misleading, so I prefer to add a few notes myself.

Anyway, I now prefer to record as a “precaution,” rather than staring at a bunch of transfers at year-end and ending up filling in random data. Stop-loss is for the position, records are for the mindset… that’s all for now.