Vitae is an organisation championing the personal, professional and career development of doctoral researchers and research staff in higher education institutions and research institutes.
Their website has a number of useful resources for graduate students. One of them is a document titled "The seven secrets of highly successful PhD students". Here's my summary:
1. Keep in touch with your supervisors.
2. Write often.
3. Be realistic about your contribution and yourself (being different than your PhD).
4. Avoid distractions.
5. Treat PhD as a job.
6. Ask for help.
7. Understand it's all about persistence.
Many thanks to Dina Said who let me know about this resource.