Hi Mark,
I would try to avoid those 'dead' areas of water where there is little flow. It tends to be less well oxygenated and less attractive to the fish.
The Usk was very clear on Saturday and therefore, when it's like this, you need to approach to fish with extreme caution. Remove the indicator. Use the tip of the fly line to detect takes. In some cases you may even see the fish to your fly. Use a long, tapered leader - 12' to reduce the chances of spooking the fish but not long enough to effect turn over. Try not to cast too long a line or you'll need to false cast more and there are probably fish between you and the one you are targetting. If you do need an 'indicator', try a klinkhamer special - nice and bouyant with the nympg trailing behind - either NZ style or with the dry on a dropper.
Keep it simple and deliberate and focused - and you'll find you find more fish.