Some useful references are as follows.
For writing and research skills:
Booth, Wayne C., Colomb Gregory G. and Joseph M. Williams, The Craft of Research, University of Chicago Press, 2008
Feibelman, Peter J., A PhD Is Not Enough!, Basic Books, 2011.
Strunk, W. Jr. and E. B. White, Elements of Style, Longman, 1999
McCloskey, Deirdre, Economical Writing, Waveland Pr., 1999
For presentations and delivery:
Reynolds, Garr, Presentation Zen: Simple Ideas on Presentation Design and Delivery, New Riders, 2011
Pink, Daniel, A Whole New Mind: Why Right-Brainers Will Rule the Future, Marshall Cavendish, 2008
Williams, Robin, The Non-Designer’s Design Book, Peachpit Press, 2003