This site has some good information about marketing online. Check out some of the articles in the Start and Grow categories.
In general, I would suggest identifying what your startegy and goals are for implementing any kind of search engine marketing.
- Are you trying to drive awareness, volunteer sign ups, donations, etc.?
- Is there a budget for paid advertising or are you planning on working on only (free) natural search engine rankings?
- Do you plan on hiring an outside resource to implement the SEM (search engine marketing) or will you being doing it yourself?
Once you ask yourself some of these basic questions, there is plenty of useful resources out there to learn more about SEO and general SEM. There are some really good blogs out there like SEO Book or check out Bruce Clay's website for some helpful info. It is important to understand that with search engine marketing, it is not an overnight solution. It takes time and work no matter if you pay for it or do it yourself. So figure out what your goals are, do some research, and find out what the best mix is for your business.