We change Congress to a more Euro-style legislative body with many, many parties. This way any fringe parties can win their 1-4 seats, speak their lunacy, and have almost no real power. Also, this would mean no single-party majorities unless that party was extremely popular. So most of the time, by necessity, the people elected will actually have to compromise and negotiate.
Elected officials who take special interest money must not only disclose all contributions, but they must wear advertisements for those special interests on their clothing like a NASCAR driver.
2 consecutive term limits for all elected officials. You can run again after sitting out a term, but you only get 2 terms consecutively.
Performance-based incentives for things like passing a balanced budget, passing bills with a low pork index (independently calculated), and reaching certain productivity metrics (also independently calculated)
If you run for another office, you must resign your current elected position