The trick for a community-based organization is to decide which ones to pick. This choice becomes even harder when you decide to work not just on local issues, but national or statewide concerns as well. The process for choosing issues doesn't really change. It should be immediate, specific and realizable.
Vacant buildings are a problem.
That building we want torn down by the end of the month is an issue. That's not a good issue, especially for a new group. But most good community organizations can point to victories that any sane person would say were far beyond their reach. It remains true, though, that figuring the odds on winning is an important first step. The key is to calculate.