I got a job tutoring first year students (I'm a masters student), which has really forced me to understand the course material thoroughly. Answering the same questions over and over about report and essay structure, referencing, and the importance of reading the assignment outline has made me a lot more aware of these when working on my own projects too. Also, it's not officially part of my job (i.e. I don't get paid for it), but I always offer to review drafts and critique students' structuring, language use, and grammar, which really reinforces good habits when I have to write something myself.