I agree with kwik6 the plastic will help out alot.You also may use a dehumidifier to reduce condesation. If you plan on renovating , look into a hrv system . (Heat Recovery Ventilater)
or air to air exchanger. A hrv provides fresh air from the outside without losing heat. It greatly improves climate control
and helps with humidity. It hooks up to your exsisting ductwork
so installation is easy.Call your local Hvac shop.