(this is a first draft - feel free to copy this, expand it, and spread it around).
Existing GOP Organizations - They're out there. Call MIGOP in Lansing or use the website to find one. Call your local County and District Chairmen on how to get involved. They don't bite, and could really use your help. Just being social with other Republicans is helpful - and keep it positive!
Meetup.com - Yes, it costs money, but you can organize local Republicans in your area looking to shoot-the-breeze and maybe do something positive.
Precinct Delegate - Elections are held in August of even years. But you can call your County GOP and ask if they can add you if there's nobody already in your precinct. They go to County & State conventions, and are active "in the party". Want Saul Anuzis out? Want a say in party politics? Be a precinct delegate.
Read Voraciously - Randall Thompson has a recent post with great Conservative thinkers. Russell Kirk, Burke, von Mises... also read about how to campaign. Read up on campaign finance laws. Read up on politicking and how to play the game.
Blog! - Posting on RightMichigan helps. This site has grown with each of us posting and haggling. Contribute, post, and respond to posts on here and all the other Conservative blogs.
And finally:
BUILD CONNECTIONS! - Politics is a "contact sport". It's not what you know, or how much you know ideology. It's about WHO you know. Get out and talk to people.
- Talk to strangers (it's okay, you're adults now).
- Talk to party insiders (the worst they do is delete your email, but most want what you want)
- Talk to reporters and other vermin (just wash your hands afterwards)
- Be a "people person"!
In the end, running for office or changing party politics means convincing people to your way of thinking. Or them convincing you.