Ireland has a system that looks a bit better than ours, but still is criticised and it's also up for reform (says Wiki).
en.wikipedia.org
Off the top of my head, I'd make it an elected position, at least in the majority, and those elections based on PR so that minority voices (right, left, and other) get a better voice.
A large salary, a limited term, and the highest standards of public office mandated and enforced by constitutional and criminal law rather than by convention.
The only way to get better politicians, imho, is to break the endless cycle of cronyism and corruption.
No second jobs if you're an MP or "Senator" (if that's where we're heading). No non-executive board positions. No acceptance of jollies or hospitality. Full disclosure of potential conflicts of interest where family is involved.
In essence, the same rules that the low level seat-warmers like me are obliged to follow if we're dealing with potential suppliers or family members as part of our role.
Enforcement and investigation of the above rules conducted by an independent judiciary, rather that the politicians, or a subset thereof, themselves.
Doubt it'll ever happen though...