See whether flashing is provided over the window caps to turn the water and if so whether the flashing is in good condition.
Look for holes or large cracks at window sills. They will appear if the inside stool or ledge is not well nailed. They may exist where parting strips and pulley stiles meet the sill or where the top sill joins the wood or brick subsill. If backband molding is used around the top and sides of the outside casing, see that it is nailed tightly against the casing.
Probe between the frame and the wall at each side of the window to see whether calking is needed to keep out dampness and cold. Examine the windows for broken panes and loose putty. Examine shutters, storm sash, screens, and awnings, including fittings and hardware, for defects.