Recently, I saw everyone talking about block builders and bundles. To put it simply, retail investors really don't need to turn themselves into engineers… You just need to know: your transaction isn't necessarily "processed in the order you submit it" into the block; it might be packed and taken away by someone else, which sometimes shows up as slippage suddenly increasing, or transactions behaving strangely even though you haven't changed any settings.

So I personally think, knowing this much is enough: don't blindly believe "if I click first, I get processed first," and don't rush into the chain during congestion or maintenance, especially these past couple of days before and after a major chain upgrade, when everyone is guessing whether they'll migrate. The more active it is, the easier it is to slip up.
If you can only keep one habit: always split large orders into smaller ones before placing them.