Lead with the line that matters most
Instagram truncates a caption in feed after the first line or two, so whatever earns the "more" tap needs to come first: a real hook, not a warm-up sentence. If the first line could be cut and nothing would be lost, it is in the wrong place.
Give people an actual reason to comment
A caption that ends on a genuine, specific question earns more replies than one that ends flat or with a generic call to action. The question needs to be one your audience can answer from their own experience, not a rhetorical one nobody is going to type an answer to.
Write for the save and the share, not just the like
A caption that packages something useful (a specific tip, a checklist, a clear opinion worth sending to a friend) gives people a reason to save or share the post, not just react to it. Saves and shares signal that a post was useful in a way a like does not.
Keep hashtags out of the caption's main flow
Since hashtags now function more as categorization than reach, cramming them into the middle of a caption mostly just interrupts the read. A short set at the end, or in the first comment, keeps the caption itself readable while still doing the categorization job.