My experience with charities is mixed. Some, usually smaller one-man, or most one-woman-shows are effective and just do what they stand for. The bigger, the more problems come up. Once you get popular, there is a risk that you take more care about your popularity than your cause. So some advice from a communications experts point of view.
1. The cause is important, not you.
2. Focus on what you are doing, not who is doing it.
3. Being a volunteer doesn't mean you don't have to be committed (and accountable) for your engagement. It actually means you HAVE TO be committed and accountable.
4. Tell everyone about what you are doing. It doesn't matter who you are or where. The more public support, the more safe you are.
5. Any information you give to members and public should be under public domain or creative commons licence.
6. No titles, unless it is required by law. A president of a charity sounds like a lot of administration, even if it is unpaid.
7. Understand the power of online hubs. Get connected to the right people to spread the word about your cause on large scale.
8. Tell stories about every project you did, in detail and in time.
9. Raise money for a specifc detailed project, not just for "we help children in need".
10. Have fun, and let others have fun too. The cause is serious enough.