I haven't fished Banagher for a long while but it had become more difficult when last I visited. The bream didn't seem as widespread and the roach not as prolific.
But in Ireland, the same things still work. First of all, a pre-baiting campaign - perhaps four or five hours before you want to fish. Then plenty of bait going in as you fish, and in deep swims, using a jam-pot of a feeder or big, very solid balls of groundbait to get the feed down.
I think just about any bait will do the trick for the bream and roach - maggots, worms, casters and even more exotic baits. For bigger roach, it's hard to beat bread flake, and timing your fishing to go on until last light, when the bigger roach come on feed.
But it's a case of bait and more bait on the Shannon generally.