Implement the US system again but with 3 major changes:
1) Term limits on all politicians including congress and judges: no more Kennedy's, no more untouchable incumbents, no more planting seeds in the courts, etc. Why should my liberty suffer because I'm outnumbered by stupid people?
2) Mandatory sunset on all legislation: make sure all laws are relevant to the current generation and eliminate the threat of slippery slopes and end progressive "get your foot in the door" Pelosi politics. I don't like being bound by laws that were created 100 years before I was born that have zero chance of ever being brought up again (eg: NFA), especially laws that were hastily passed purely on irrational emotion after some big event. Then it doesn't matter who gets elected or what damage they cause, because it will expire and at some point in one persons lifetime he/she will be able to have that abortion or get that assault rifle and not fear one way ratcheting slippery slopes.
3) No unrelated amendments to bills: no more sneaking in crap with desirable bills to get it passed unknowingly at the last second and bypassing committee and skipping debate. No more bills titled "For X and other purposes" where X is providing money to school children while "other purposes" is banning guns, cars, and big screen TVs and giving congress a 500 percent raise while touting an "education" bill.
Those 3 things alone would eliminate the source of a lot of problems we currently face.