how can i judge that the combination is series and which are in parallel or series  if it is a complex combination?

during the transient state the capacitoars are connected n series(in complex ones like RC Circuits).but ven the steady state reached just apply node and branch analysis to check the combination..

you can apply nodal method and you can also check for symmetry if there is any  and likewise apply asymmentry or inverted symmertry or some other symmetry

 u should look for equipotential points and try to join them and symmetry also helps....try to straighten out circuits into rectilinear shapes... look for nodes etc.....practice a few problems and solve every problem that comes ur way...after a few problems... u'll get the hang of it! It will be very easy to visualize!