Here is how you guarantee centrist moderate governments.
1. Have many parties.
Forces cooperation and partnerships, coalition governments. Grinds everything radical to a halt immediately. Even good legislation can be picked to bare bones via compromise. Having sleek, simple legislation is the best for Liberty.
2. Have a None of the Above option.
If None of the Above actually wins an election, you should not be able to run again. Full reboot of candidates. This will force honest, simple platforms that have nothing to do with scaring you about the other guy, rather, forcing you to show the people why you are the best choice. This leads to:
3. Make all advertisement only about your platform.
Attack politics are a ridiculous strategy that does nothing what so ever for the people. Ban it. Make it so that you can only tell the people what YOU are going to do for them. Nothing else should be tolerated. (Nice Hair Though)
4. Severely limit the money flow in campaigns.
Force candidates back to the stump, and back to the pavement. Get them out, meeting the people. One at a time. Door to door. Massively unbalanced cash advantage for establishment party candidates hurts the people. This leads to:
5. Severely limit or eliminate all pensions for elected public service.
This will push out the establishment lifetime political class, and bring in passionate real people into the equation. It disgusts me that an 8 year term MP gets a 108k a year pension. Disgusting. This leads to:
6. Establish a one term, non consecutive term limit.
Again, it is the career politicians that are ruling the roost in all western governments. No term limits, and unlimited money in campaigns establishes nothing less than intergenerational money laundering mafia operations. It has to end. This leads to:
7. Mandatory sociopathy and psychopathy testing for all elected positions.
Let's get some people with actual moral compasses in power, eh? I have had enough of warmongers, and pork barrel spending kleptocrats posing as public servants. And finally, this leads to:
8. Limit government spending
No matter how good the intentions, there are going to be those elected that look as the public coffers as theirs, or as a money laundering slush fund. Get rid of almost all of it, and the stakes in their sickening game shrink. Give the money back to the people where it belongs. Take it out of the hands of these professional, and mildly competing money laundering mafias posing as public servants.