Here are some resources I know of:
TechSoup has a few "How To" articles in its
Funding Section.
Some examples:
"Writing a Winning Grant Proposal"
"Beyond the Case Statement: Your Grant Proposal"
"Position Yourself to Write a Superior Technology Proposal"
CharityChannel offers many resources, such as their "Grants and Foundations Review" newsletter:
http://charitychannel.com/enewsletters/gfr/
a list of grant opportunities:
http://charitychannel.com/enewsletters/dggo/
and a
grants discussion list.
The Foundation Center is a fantastic resource, especially if you're near one of their offices. They have an online grants database (by subscription), and also teach classes on grant writing:
http://www.fdncenter.org/
The firm Research Associates has a
Grantwriters Toolbox on their website.
The American Association of Grant Professionals has a helpful website, including a consultants directory:
http://www.grantprofessionals.org/
as does the Puget Sound Grantwriters Association:
http://www.grantwriters.org/
The Association of Fundraising Professionals (AFP) also has a
consultants directory.
AFP's regional and local conferences usually include grantwriting workshops. Check the national website
http://www.afpnet.org
and your local chapter (which you can search for on the national site).
Many cities have nonprofit service centers that offer grantwriting workshops. In the San Francisco area, CompassPoint is one such provider. They offer a two-day workshop called
"Writing Successful Grant Proposals."
Try Googling the phrase "nonprofit service center" or "grantwriting workshop" plus your locale and see what's available near you.
Finally,
Jossey Bass publishes a lot of books on this topic.
For instance, "The Accidental Fundraiser" by Stephanie Roth, "Demystifying Grant Seeking" by Larissa Golden Brown, "Grant Seeker's Budget Toolkit" by James Aaron Quick, and "Storytelling for Grantseekers" by Cheryl Clarke.
If you'll reply with your location, other people might know of local resources.
Best of luck with your grant.
Robert