Your local community college will have grant writing classes available. Our group paid for me to attend several years ago. My first grant was for an Artist In Residence program and was successfully written.
Advice for writing?
1. Follow Exact Directions. Grants not following the exact guidelines are not given. If it says 3 pages, it means 3 pages, not 2 1/2. The judges are very specific about following instructions to the 'T'.
2. Mail Early. Deliver it if you can. Depending on the importance of the grant, use either Certified Mail or Registered Mail, and be sure to use a Return Receipt.
3. Use All Avenues Available. Your research into the grant and then writing the grant should be extensive. Use people, books, newspapers, etc. to gather all information. Don't try to do it all yourself.
4. Write From The Heart. Grants are usually very dry reading. As long as you follow the exact directions (see #1...lol), feel free to tug on the judges heartstrings. Write to get them excited about your project! Grants are awarded to the groups who can make the judges 'see' your vision. Dry reading will win too, but you have a better shot if you can excite your judges, if you can make them visualize your program while reading your grant.