A draft is any text which not in its final form. It is work in progress. A preliminary draft may contain just a few main ideas and notes about what you intend to include. Drafts can be messy. That's the nature of a draft. It is not the final product. The one time a draft should not be messy is if you are submitting it for or approval. It would be extremely discourteous to submit a draft knowing it is full of errors or text you intend to change anyway.
You have a plan, you have some ideas and you are ready to start writing. But maybe you get stuck. The ideas are not flowing onto the page as you thought they would. You can't find the right words. Your ideas are not as clear as you thought they were. Your thought don't seem to connect.
So what do you do? Maybe you're tempted to rethink everything, start from scratch, or do some more reading. Well don't. Just write. Write! The words will come. They may not be the right ones but that doesn't matter. You can change them later. A draft is just a draft. It's getting ideas down on paper (or on the screen) so that you can work on them later. A draft is a working document - work in progress. You can't improve your writing unless you have something written to improve. Incomplete writing is better than no writing.
Writing is an iterative processSomething you do in cycles, again and again, changing with each cycle. Few accomplished writers write a text, even a short one, just once. Or if they do, they probably went over it in their minds many times before they wrote it. Once you think you have a draft which you can work on and improve, you need to prepare it for review. Even if you don't intend to submit anything for review, it's always a good plan to work as if you were.
Whether your draft is just for yourself, or whether you will submit it to your peers or an instructor for review, make sure you can answer yes to all of these checklist questions before you move on to the next stage or submit for review.