feeder fishing is best approach. Best areas are either the first few swims along the roadside or the dam wall area. I wouldn't bother going down to the shallower area at the end of the lake because the deeper area produces the best fishing.
bring a lot of bait because the bream shoals are big and will move on quickly! Ive had good sessions with balls of vitalin catapulted out and fishing the groundbait feeder with corn or maggot. corn will produce the bigger bream to about 6LB and usually you will catch some carp because there are loads of them in there and they give great sport of bream gear... the roach are good aswell and down the dam wall area you got a chance for a tench (not many are caught at shearwater...in 4 years of fishing there ive only had the 1 at 5LB)
It is one of the nicest places to fish in the country I think and offers awesome sport! if you want piece and quiet like me I advise going on the roadside or fishing midweek!