I have a progression in the key of C, the verse goes from Em to C, cycling back and forth for a while...a chorus etc... but I have a bridge that goes Cm/Gm/Dm/Am...it all sounds ok...but I cant figure out how to lead from the C into the Cm of the bridge.

Could someone please suggest some chords, or even better the theory behind selecting a chord to lead into this, in this case, C to the first bridge chord of Cm???!!! I would really appreciate any help.

In case it matters, I am thinking that the Cm and Gm chords are substituted from the parrallel C minor scale (aeolian), just in case it makes a difference. thank you.