First-past-the-post voting systems are extra dangerous. I.e. where all the votes of a district go to the winner of the district.

If instead all votes go proportionally according to what people voted, you get less extreme policies and encourage parties to build coalitions. Nobody is happy, but fewer people are extremely unhappy.

Forbid Gerrymandering.

E.g. Republican Schwarzenegger has been advocating against gerrymandering for a long time.

Force all states to cast election votes to be proportional to citizens' votes (some states do but others do not).

I realize this is just my own idea, but I think the Constitution forbids gerrymandering, by demanding a "republican form of government" in the states. The question is how this opinion would stand up to being tested by the current Supreme Court.

You can find plenty of "workarounds" in any Wal-Mart or pawn shop in the US. You can even buy a "workaround" from someone directly and avoid a background check.