I'm a naturally bad writer but somehow I managed to become confident in writing documentation, cover letters etc. For cover letters asking friends/family for feedback had helped me a lot, also for this specific topic there are a bizillion great books about the topic - amazon is your friend. Or google: how to write performance review
That said, I think depending on the kind of writing you want to do, there is probably a book/article about it.
Also what is a nice strategy that always works for me: start with brainstorming or random bullet points. Put things in order, like a 1 or 2 level hierarchy. Mark important things, throw out things you are not comfortable with. Add some details.
Then get an example text. In the case of cover letters there's always a standard structure: intro, main part, end. And then replace it with your words. Also in the case of reviews, maybe you can ask your colleagues to see how they structure their writing and even review yours before you hand it in.
That said, I think depending on the kind of writing you want to do, there is probably a book/article about it.
Also what is a nice strategy that always works for me: start with brainstorming or random bullet points. Put things in order, like a 1 or 2 level hierarchy. Mark important things, throw out things you are not comfortable with. Add some details.
Then get an example text. In the case of cover letters there's always a standard structure: intro, main part, end. And then replace it with your words. Also in the case of reviews, maybe you can ask your colleagues to see how they structure their writing and even review yours before you hand it in.