What's the best way to give students feedback on their writing?

The most effective writing feedback shares three traits — and "more corrections" isn't one of them.

1. Target the process at specific points, not the whole person. "You're a good writer" and "needs work" are equally useless. Point to the exact place and the exact move: "Your second paragraph makes a claim but doesn't back it up — add one piece of evidence and a sentence explaining it." Feedback aimed at the work, at a specific spot, is what a student can actually act on.
2. Make every comment require an action. Feedback the student reads and files away is wasted. The best writing feedback creates a revision — a specific change to make on the next draft. This is why margin-to-margin corrections often backfire: they overwhelm, and the student "fixes" mechanically without learning. A few high-leverage, actionable comments beat a page bleeding red ink.
3. Prioritize — don't mark everything. Choose the one or two moves that will most improve this piece (usually structure and evidence before grammar). Correcting every error at once teaches little and demoralizes; a focused revision target builds a skill that transfers to the next piece.

The reason teachers don't do this consistently isn't that they don't know it — it's that writing specific, process-focused, prioritized feedback for a full class of essays is exhausting. Generating a strong, specific first round of comments per student — that you then adjust — is how the good practice survives a real stack of papers.