"What can I do to help?" Undoubtedly, in the volunteer world, the most magical and important words you can ever speak. Heck, in about any situation, even married life, these are magical words that can change the world you live in. But for volunteer projects, leaders and workers don't always ASK for help. It has to do with saving face; or not wanting to be a bother; or being afraid to be too pushy; or thinking that someone else should read their mind and do something; or whatever.
So the solution is to pose the question: "What can I do to help?"
When you see someone struggling with a task or project; ask. When you notice you're not being very productive because someone didn't really give you a job; ask. When you know someone is behind the 8-ball; ask; When you can tell someone is way behind on their schedule; ask. Just put this magic to work -- ASK; "What can I do to help?"