Tips and tricks: Put your name in the Subject: field (e.g., "For Sale by [Your Name Here]") and you can reuse it any time you have something to sell. Use Replies to your original post to post more than 4 items or photos, and use Replies to indicate what has been sold.
If everything in your Post gets sold and the Post itself is looking long and worn out, Delete it and start a fresh topic, again with your name. You shouldn't need to have more than one post with your name at any given time.
Note the restrictions on attachments. Spreadsheets are small enough, but large photos can be problematic. If a photo is too large, try reducing the size or saving it in a format that is more Web-friendly.