I've always been quite ambivalent about political parties. I've never been a member of the 'eat your ballot' set -- having a tool, however poor, by which events can be influenced and then not taking the fifteen minutes it takes to use it has always struck me as silly. However, I have never belonged to a party and never felt even close to being convinced (and people have tried) that sinking energy into some party or other is the most important way to create change.
I want to point people towards the first part of a multi-part essay called "Rethinking Political Parties" by long-time British radical Hilary Wainright. I don't agree with everything she has to say. For instance, she seems to focus on identifying "assumptions that underlie habitual political responses" in existing organizations in order to figure out how to move forward. I think that's useful, but I think that it is also essential to look at not just "assumptions" but at the actual forms of organization and how they influence the shifts in a group's politics over time regardless of initial intent.
However, in asking questions about how power works, what agency is, how knowledge is produced, and so on, Wainright is wrestling with the sorts of questions I think we all need to be reflecting on if we want to direct our actions in ways that don't just result in more of the same.