I agree on the beaching them thought process. That's how we bring them in if the net happens to be a bit up or down stream from us. You just have to make sure not to horse the fish in hard as beaching tends to put stress on the setup.
If you are going to use a net though, simply make sure it is large in size, although easy to carry, with larger size netting, and a steel frame because you should be hauling in 5 to 10 pound steel head. Of course the best method still is bring them close enough to shore, pin them down, remove the fly, and let them go back to where they came from, so the next person can enjoy the same moment of fun as you have a steely ripping line off your reel.