How long should a hook be?

Usually one or two sentences. It has to fit in what the feed shows before the rest of the post is cut off.

Should a hook be a question?

Only if it is a real question the reader has. Rhetorical questions ("Want to grow faster?") are among the weakest openings because they promise nothing specific.

Can I write the hook last?

Often it is the best way. Write the post, then look for its most specific sentence and move it to the top.

Answer

What makes a good hook?

Quick answer

An opening line specific enough that the right reader wants the next one, and honest enough that the post delivers on it.

What it's not

It is not clickbait. A hook that promises more than the post delivers ("This changed everything") wins one click and loses the reader's trust for the next ten posts.

The hook is the opening of a post, the part a reader sees before deciding whether to keep reading. On LinkedIn, long posts are shown truncated in the feed; on X, the whole post may be the hook. Either way, the reader decides in a line or two.

Specific beats clever

The most reliable hooks are concrete. Compare “Some lessons on pricing” with “We doubled our price in March and lost two customers out of forty.” The second tells the right reader, someone who has agonised over pricing, exactly what the post is about and why it might be worth their minute. It also makes a claim the rest of the post has to back up, which keeps the writing honest.

Good hooks tend to come from one of a few places: a number from your own work, a decision and its cost, something that went wrong, a belief you have changed, or a precise question your audience is already asking. None of those can be invented without it showing, which is the point.

Openings that cost trust

The hooks that hurt a presence over time are the ones that oversell: “Nobody talks about this”, “This will change how you think about X”, fake cliffhangers, a first line in capitals. They can win attention once. But the reader who clicks “more” and finds an ordinary post remembers it, and the next hook from the same account has less credit.

There is a real case for bolder openings: a feed is crowded, and a timid first line is easy to ignore. The way to be bold without overselling is to lead with the strongest true thing you have. If the post has nothing strong and true in it, no opening line will fix that, and the better move is to keep the idea until it does.

A working method

Write the post first. Then read it looking for its single most specific sentence, often buried in the third paragraph, and move it to the top. Check that the post delivers on it. When you are writing for several networks, the same idea may need a different hook on each: a standard X post has 280 characters in total, a LinkedIn post up to 3,000.