[NeoTar]

You should look into the German system.

How it is supposed to work is that 50% of representatives are 'local' representing a region (of roughly 300.000 people) and the remaining 50% of representatives ensure proportionality.

So, imagine the CDU (centre-right party) wins 40% of the voting share, but 60% of the seats, the SPD (centre-left) 30% of both voting share, and seats, the Greens 20% of the share but only 10% of the seats, and the FDP 10% of the share and no seats. The seats to ensure proportionality would be distributed 20%, 30%, 30%, 20% respectively.

There are a lot of subtleties to the system to ensure true proportionality that I won't go into right now, and tend to lead to the parliament growing (if things work perfectly there should be 598 seats, but currently there are 736), but broadly the system works.