Brown offers several classes on creative writing (look them up on BOCA under English Literature EL0011). Daniel Acevedo, who actually took one of them, says: "You might want to read the section descriptions and email the professors with what is it that you are looking to get out of the class."
I've worked a lot with the Brown Writing Fellows (thanks to my advisor David Laidlaw), they're pretty good (but nobody is as good as Trina Avery). They will patiently edit your papers, but if you'd rather figure out first the principles of scientific writing, see the resources above. :-)
Presentation (talks):
The Sheridan Center for Teaching at Brown is the most amazing resource you could dream of. True, their focus is on teaching, but the presentation skills they teach are just as useful for research talks. They've published an excellent booklet on Persuasive Communication (go on, read it; it lays out the basic organization of a talk, among other things). The Sheridan Center runs a Teaching Certificate Program (the grad Curriculum Czar, aka the CS - Sheridan Center Liaison, can help you register). If you ask the Center, they will come to your talks, videotape you, and give you feedback.
Spike (John Hughes) gives a set of excellent presentation tips; check out the section on thesis proposal talks as opposed to thesis defenses. I can't find it on is webpage, but he said on multiple occasions that talks should start with a teaser (a glimpse at what we'll know by the end of the talk); here's a more formal version (with Simon L Peyton Jones and John Launchbury): How to give a good research talk.
John Pinto of Stanford University lists a few Do's and Don'ts for Brief Research Talks (from Gordon H. Bower). You may agree or not with Bower's observations; they're still interesting.
Brown University operates a Rhetoric Fellow program. The Rhetoric Fellows are veteran Writing Fellows who receive additional training in coaching public speaking. These fellows complete a training seminar in speaking and go on to help students with oral presentations of all kinds. They're pretty good; they can teach you a bunch of tricks, from breathing and projecting your voice to stress-management exercises. You probably want to come to your rhetoric appointment with a pretty well-organized talk (see above) -- they'll help you polish it.
Last, Brown offers several classes you may find helpful (cleverly disguised under the "English for International Students" EIxxxx label on BOCA). Yes, their focus is improving one's American accent, but for the final exam you will be asked to prepare a short presentation; the EI-team will provide an audience, videotape you, and give you feedback.
The Writing Fellows can help you refine a poster, but really, the most sensible thing to do is print
a real-size draft of your poster (A4 sheets taped together), put it up on a lobby wall with a stack of post-it-notes and pencils next to it, and ask your friends to mark their comments directly on the poster draft. The Brown SciVis group has a long standing tradition of reviewing posters, we'll gladly help.
