The best flies seem to hint at their ancestry. For example there are some wonderful stonefly imitations, but the good old stick fly does just as well. Many rainbow trout fishermen are brought up on lures and wonder why they are not so effective for brownies. Brown trout are far less aggressive than bows. They are less likely to take a lure.
Most anglers therefore rely on imitative patterns.
Those lures which do work for brownies tend to look like fish and thus fall into both camps. The only time when you can really catch brownies on lures is at the beginning of the season when they are really hungry. It encapsulates the best approach to brownie fishing. Spot what naturals are about. Brown trout can be very selective to the point that they will sometimes only take imitations that look like a nymph breaking surface, while at other times they will only take the adults as they return to gently lay their eggs in the surface film.