Here are some approaches to try when looking at painting:
Peel off the protective outer layer of the painting to get to the real one underneath (use your fingernails and get stuck in).
Try looking at the painting from a long way away- brushstrokes that seem clumsy and rough from a few paces off are often more effective from space.
Try surprising the painting. Pretend you are just passing through and mutter something about looking for the loo, then turn sharply and catch the painting while it is at its least self aware and most relaxed.
Crawl toward the painting like a snake with your eyes down, chanting gently. Bring fresh meat as a tribute.
To really mix things up, approach the painting with a hand mirror outstretched in your left hand, and with your right point an accusing finger. Wear dramatic make-up and some of those vampire teeth.
If this fails, try intimidating the painting. Sprint toward the work as if you mean to tackle it. At the last minute, lurch into the gallery wall, which is usually pretty soft (test it first!). Repeat as necessary.
No painting can be properly appreciated without 3D glasses.
For installation pieces, remember that the key thing is that you showed up.