As I told you earlier the correct methods are different for different people. Some combination suits one while for some other combination of the subjects suits.
the paper 3rd includes polity and related questions so if you choose it as an optional paper then it become beneficial for both the papers to study political sciences.
Similar is the case of history and geography they are part of paper 3. So if you choose these as optional subject than definitely your studies for paper 3 are also getting easy.
And for most these subjects are easy to understand also.
So you can choose political sciences as an optional subject if you want. However before deciding for yourself take a deep look on syllabus then choose according to your convenience.
Hope you find the information helpful.