The Cotswolds is a large area so stick to either North Cotswolds (N of the A40) or South Cotswolds (S of the A40)
The north is probably the more attractive but is also overflowing with tourists. There you have Broadway, Chipping Camden, Stow, Bourton on the Water (also known as Brum on the Water), the Slaughters, the Swells and a myriad of places in between.
On the edge of the north and almost classed as south is Burford. Around there is Bibury (Arlington Row), Northleach, Eastleach and further south is Painswick, Slad (Laurie Lee country) and other quiet villages.
Look at a map, pick an area and walk is your best bet.