Where are you going to be staying? There are some monster browns and big rainbows for the first couple of miles below the Bull Shoals dam. The further down you go, the numbers will go up and the size will go down. Past Cotter and you may not see a fish over 12".
It is a deep and fast river, so wading is difficult. Boats are pretty much a must, and a guide is highly recommended. Ron Yarborough
is maybe the best guide I've ever fished with anywhere.
Hoppers early in the morning over the grass beds. Big articulated streamers on a 8-10 wt full sink are good for big fish. You won't catch many, but hang on for the ones that you do. When it gets hot you may have a shad kill, and that supposedly is the best time to fish.
Take note of the catch and release zone under the dam, and the signs on either side of the river that mark the no fishing zone (it's maybe 50 yards under the dam). Game Wardens are pretty serious about it.