Start with a rough practice message: "Hi Alex can we meet next week I need discuss poster maybe Wednesday send me when free thanks." The words communicate a general intention, but the reader has to work to identify the request.
First check purpose: you want to arrange a poster discussion. Then check the details you actually know: perhaps Wednesday afternoon is available, but no time has been agreed.
Revise the message in a useful order
A clearer version is, "Hi Alex, could we meet next week to discuss the poster? I am free on Wednesday afternoon. Would that suit you? Please let me know what time would work. Thanks, Mina."
Now check form: sentence boundaries, punctuation, spelling, and the phrase "to discuss." The revision does not invent a confirmed meeting or imply that Wednesday is the only possible day unless you intend that restriction.
Finally, read from the recipient's perspective. Can Alex tell what the meeting is about and what reply is needed? If the message references an attachment, confirm it is included before sending. Practice another message with a deliberate missing detail and ask a partner to find it. Separate review passes help you improve accuracy while keeping the actual communication task visible, especially when a message sounds fluent but still leaves the reader unsure what to do.