Much of my work is about providing students and scholars with occasions to experience their competence as writers. This also means I provide them with occasions to experience their incompetence. If you want to know how to improve at something, you have to give yourself opportunities to run into your limits. Give yourself conditions under which a task can reasonably be completed and then make a sincere attempt to do so. Now your success or failure tells you something. But do keep in mind that the attempt will rarely be a complete failure or a complete success. The idea is to discover more exactly where you can improve.
When it comes to writing, and especially academic writing, the composition of a paragraph offers such an occasion. Any attempt to write a paragraph about something you know will tell you something about how well you write. It is important here not to attempt to write something you merely should know, something your teacher has assigned or your editor has demanded. In such cases, your knowledge is part of what you are testing. If you find it difficult or even impossible to write something under these conditions, you may be running into the limits of your knowledge, not your writing ability. So pick something to write about that you know.
Also, make sure you give yourself a specific time and place (a moment) in which to demonstrate your competence. A good academic writer should be able to produce a paragraph in 18 or 27 minutes (followed by a 2- or 3-minute break). If you don’t give yourself a reasonable amount of time, you’re not really demonstrating a lack of writing ability. If you give yourself too much time, you’re not demonstrating a skill that is very useful in the long run. When the problem of knowing something has been settled, it shouldn’t take you two hours to write 180 meaningful words about it. If it does, that’s what you want to work at.
This is the most important thing about observing your competence as a writer. You have to set up an experience that is repeatable. You have to be able to sit down “at the machine” on a regular basis and do the same thing, just as an athlete can drill and a musician can practice. Practicing means working under conditions where the difference between two sessions is mainly your own competence, which is gradually improving. (Actually, you’ll experience setbacks too, but in the long run, if you’re doing it right, you should experience getting gradually better.) You don’t want to sit down and do something where success depends entirely on situational factors. You want your success to depend mainly on your skill as a writer.
Under such conditions, you’ll notice, your failures and disappointments become meaningful as well. In fact, you will be learning from them whether or not it seems that way in the moment. Athletes get stronger even when they’re having a bad day. Musicians become better even if they spend the entire session making mistakes. The next session will be different and the difference is simply the experience of the last session. It’s probably true that an important difference between people who are very good at something and people who are merely capable lies in how willing they are to experience their incompetence on a regular basis. So give yourself a moment or two every day in which to observe how good you really are. It takes a little courage, but it gets better.