They like to be pruned, and they need acid soil. You should sprinkle some azalea/rhododendron food around them early each spring, very gently rake it in a bit (be careful, they have shallow roots), and if it isn't going to rain within a day or so, water the plant. Repeat this procedure after blooming is finished, but no later than mid-July.
Prune them immediately after they have finished flowering, or you'll be cutting off the buds that will become next year's flowers. Don't prune away more than 1/3 of the living branches, and remove all deadwood. If the plant is already the size you want it to be, then just clip a few stray ends here and there to keep the shape nice.
The do need some sun. In the wild here in Oregon, rhodies grow around the edges of the forest, just inside the tree line, and in little open areas among the trees. In those areas, they get the early morning and/or late afternoon sun. You won't find them growing in the dark depths of our rainforests or out in the middle of a meadow, just around the edges. Deer prune the wild rhodies.