I have decided that I am completely useless at blind fishing nymphs. So was wondering, is it worthwhile to blind fish a dry fly over good looking water when there is no obvious 'raises'. At-least with that method it should be more obvious when a fish takes my fly?

Both, I'm no expert but why not simply use a dry fly as an indicator?

Can not be bothered dealing with the tangles which often occur when using a two fly combo.

A lot of the top guys explore likely water with a dry fly. Something like a #10-12 Royal Wulff is ideal for the role. Most fish will rise to take a fly off the surface...which is interesting as they generally won't take a nymph a foot above their head. The Dry Fly and dropper is a pretty useful technique provided you're not getting tangles, however there are a couple of disadvantages with it. Firstly the nymph doesn't move as naturally. Secondly You tend to be watching for either dry fly strikes or nymph strikes (ie dry fly dropping). Therefore if you get a strike on the nymph when you're expecting the dry you tend to miss it. Michael also brings up a good point in that when the cicada season is on fish are very willing to travel long distances to take a surface cicada. This is the perfect time to explore likely water...although fish are spooky then a cicada is likely to get as many refusals as takes. Therefore I'd say that your best bet is a nice size 10 or 12 Royal Wulff. And plus...this way you get the delight of watching a trout engulf your fly.

When its calm I often use the dry/nymph combo, but I want to give the dry fly my complete attention so going to avoid it for the time being.

Yeah definitely tie it off the bend of the hook, I don't really know why more people don't do that eh.

Big Stimulators are always good for that work too Militaris.

I've been blind fishing with a green humpy into the heads of the pools. Works great this time of year on rainbows. I started with a nymph combo but they were just taking the dry so off came the nymph. I dont think it really matters what pattern - just something big and they seem to smach them. Not sure about browns - I dont get to fish to them much.

Try it you'll like it.

yeah the theory is good... but i find that you tend to strike too fast on a dry fly strike or two slow on a nymph. Possibly this is just my inexperience.