Something that I <em>really </em>recommend and that students often don't think of doing is using models. Depending on the type of writing you want to focus on (emails, academic essays, exam writing tasks, letters, articles...) look for a high-quality piece of writing in that particular style and analyse it.
<ul><li>How has the writer structured the text? Have they used linking words? How?</li><li>What grammatical features have they used? Do they use the passive or active voice? Which tenses have they chosen? Do they use conditionals? Noun phrases?</li><li>Are there some sentences that you can "steal" and adapt for your purposes? Emails, for example, contain a lot of quite formulaic language that you can use again and again (I'm writing to you in reference to...; Please confirm....; Please let me know as soon as possible whether....). This is a very useful exercise and you can do it with a lot of writing tasks, including articles and essays. The important thing is to try to look for interesting chunks of language
(phrases) rather than individual words.</li></ul>
There are lots of great resources available online but feel free to get in touch with me if you'd like some advice!