Gerrymandering can help a minority stay in power simply by canceling out the votes of the majority. That is one of its many baneful effects. There are two ways to mitigate it: cut politicians out of the redistricting process or going over to proportional representation.
What do you mean by “proportional representation” ? My example assumed just two parties, but with Green, Constitution, Libertarian, The Rent’s Too Damn High, etc. it would be impossible to represent all parties. If you actually cut the district lines for a State such that each district contains the same percentage of each party as the State does overall, then the minority parties would never get a seat.
Personally, I favor letting a computer do it by minutes and seconds of latitude or longitude. Each district would be as wide as it needed to be to include the population of a district — roughly 700,000 people — and then a new district would begin. So you and the guy across the street might be in different districts, and people 500 miles away are in the same district as you are because they live at the same longitude. Districts would slice right across major cities and include just a slice of it but also include rural populations from the other side of the state. That would make it more difficult for Congressmen to bring home bacon for the locals, and they’d spend their time on issues that affect a broader cross-section of the people in their state and — shudder — maybe even the whole country.