Since pore size tends to be genetic there is so much you can do to change it. In general keeping skin well cleansed and extracted will keep the pore size somewhat under control. Enlarged pores are a result of accumulation of dead skin or sebum (oil).
Chemical Peels are a good option, as the peels will give birth to fresher newer skin that is well hydrated and not clogged.
Prescription strength Retin-A use over a long period (over months and years) may help decrease pore size as well. We have various strengths of prescription strength Retin-A available for sale at Skin Specifics.