If you want politicians, the media and the general public to take your concerns seriously and treat your tea parties like political demonstrations rather than wing-nut circuses, here are a few things you could do to help your cause:
1. Stop inviting Joe the Plumber to speak at your events. The man has proven himself to be a complete idiot on the subjects of economics and foreign policy. If you continue to treat him like a pundit, you will continue to be considered ignorant by the rest of us. You might as well invite Britney Spears -- she'll draw a bigger crowd, and nothing she says can be any stupider than many of JtP's past public proclamations.
2. Stop harping on Obama's birth certificate. That fake issue has been completely discredited. He did produce the birth certificate. He was born in the U.S.A. If you keep peddling that snake oil to the wingnuts, your events will continue to be looked on as medicine shows rather than political rallies. I've noticed that very few birthers were concerned about the fact that John McCain was born in Panama (I'm just sayin').
3. Invite Jesse Ventura to speak at your events. He shares many of your concerns with the growing U.S. tax-and-police state. He also has cross-over credibility and is truly independent of any political party or media empire (although he does have a book to plug).
4. Put some emphasis on issues that liberals can't (or won't) argue with. There is a lot of common ground on the subject of civil liberties (such as the current proposal to collect DNA from anyone arrested, before conviction). If you spend some time talking about the things you have in common with the ACLU, liberals will stop laughing and do you the courtesy of listening to what you have to say. They will be much less likely to tune you out when you bring up your other concerns if they have already treated you like fellow citizens deserving of respect.
5. When you see some idiot at one of your events carrying a homemade "Obama = Hitler" sign, ask that individual what, specifically, Obama has in common with Hitler. Then explain why Hitler is in a class which invites few legitimate comparisons. You don't have to censor anyone, but at least try to educate the ones who are making you all look bad.
I disagree with many of your positions, but I think that one-party rule is bad for democracy. Watching the Republican Party become a shrinking, marginalized joke troubles me. Without a credible opposition, I shudder to think what the Democratic Party may become. Ideally, I would like to see several viable parties hold seats in Congress, with a coalition required for a working majority. That would keep the radicals in any party from ramming things down everyone's throats (because the minor parties would abandon the coalition in that case).