Recently, I saw someone watching whale addresses and preparing to follow their trades.

Now I’m a bit afraid of this impulse to "buy in when seeing large amounts."
To be honest, a single large purchase by a whale doesn’t necessarily mean building a position; it could just be hedging, or even reversed off-chain, with the on-chain activity just a shell to hedge risks.
Especially now, with some places tightening taxes and compliance, and deposit and withdrawal expectations fluctuating, large traders prefer to hedge to suppress volatility.
Small investors following along are very likely to get caught off guard.

My own approach is pretty simple: first, see if they are accumulating in batches and whether there are signs of opening opposite positions at the same time.
Then check if they are moving coins back and forth between CEXs and lending platforms.
If something feels off, I start with small amounts to test the waters, treating it as “paying tuition to buy information.”
Then I observe further.