Resources on doing research
Peter Feibelman has written a good short book on doing research, and related skills, A PhD is not enough. The book isn’t online, but there is a nice review by Ross McKenzie, of the University of Queensland.
John Wilkins of Ohio State University has assembled a set of one page guides to various research skills.
David Mermin of Cornell has written a lovely essay on Writing Physics.
Economist Paul Krugman, of Princeton, has written two informative essays about doing research, from somewhat different points of view, How I work and Incidents from my career. Many of the ideas in these essays apply also to research in the physical sciences.