Dry Fly Time...

Of course you can catch fish in the winter time on dries.  Fly fishing is not restricted to just spring, summer and fall, any more than trout are restricted to eating only sub-surface offerings in the winter...it's just more infrequent, more difficult, and usually the flies are very small.  Now, here comes spring!  Bugs abound...yes...so let's be efficient. 
1.  It's not bass fishing.  Don't just start flinging some dry fly out in the stream to see if something bites.  Now, I know that sometimes that can be successful, but what about the times when you make the great cast with poor timing, and the fish rises three feet or more away, just as you begin another cast?   When trout start rising, often they are methodical, rising at some sort of interval.  Not exact, but you can tell.  You can cast ten times and catch nothing, or wait a while, observing the pattern, then target the hungry fish in the area and on his time line.
2.  Can't tell if or what is rising?  Bend over!  Yep, bend down to the water, and look across the film.  This is when you see what is really going on...you got to think like a trout if you want to catch one.  Use a monocular or binoculars to look down and upstream to see if there are insects rising or falling, or if there is just nothing going on.  Fish smart...catch more and larger pescados.
3.  Be careful about your silhouette against the sky...if fishing an open meadow, your shape against the background will be something different to the fish, maybe a predator in their mind...think like a fish...
4.  Parachute adams, caddis, ants, midges...all proven and time tested...don't get too fancy.  Size matters more than anything else.
5.  Minimize false casting, and cast away from the fish, especially in very clear water- trout are watching for things above them that don't make sense.
...keep the rod bent...