For all scientists
There are many resources, just a web search away, on skills you need to be a successful research scientist (often equally applicable to other careers). Below are some we have used in the lab, as well as in Bachelors and Masters courses:
"Ten simple rules" guides on writing, presentations, collaborations, networking and more from PLOS Computational Biology
Uri Alon's excellent collection of mentorship advice
Science Careers features frequently updated advice columns; here is a collection on Balancing career and family
"Q & As" from Current Biology features informative and inspiring personal career stories and views on topical issues
The Sticky Wicket (penned by "Mole" and other secretive characters) in Journal of Cell Science is an amusing and illuminating collection of articles on the trials, tribulations (and joy) of doing science
Tips on making a great poster from Cornell Center for Materials Research
David Stern's frank blog on "How to Give a Talk"
Tips on giving a good scientific oral (and poster) presentation - slides from my own seminar
The 1-hour workday - encapsulates one key way to get the writing tasks done
From William Strunk, Jr. and E.B. White, The Elements of Style, Fourth Ed., Allyn & Bacon: "Omit needless words. Vigorous writing is concise. A sentence should contain no unnecessary words, a paragraph no unnecessary sentences, for the same reason that a drawing should have no unnecessary lines and a machine no unnecessary parts. This requires not that the writer make all sentences short, or avoid all detail and treat subjects only in outline, but that every word tell."
For prospective (or current) Principal Investigators
At the Helm - Kathy Barker's must-have guide for new (and old) PIs
For potential PIs invited for interview: Leslie Vosshall's advice on the "Chalk Talk"
How to run a Selection Panel for grants (or anything else) - thoughtful reflections by Nicolas Le Novère
Your toughest experiment: taking the lead in the lab - different viewpoints and tips on how to be a successful PI
The Awesomest 7-Year Postdoc or: How I Learned to Stop Worrying and Love the Tenure-Track Faculty Life - Radhika Nagpal's pragmatic viewpoint on succeeding at (and enjoying) the first few years of running an independent lab