To the beginning collector:
Do your homework. Read art books, catalogs, reviews, subscribe to art magazines like Art in America.
Look, look and keep looking at galleries and museums. Attend lectures. Set aside tour time when you travel to keep exposing yourself to art. If you can, take docent courses and volunteer at the local museum.
Did I forget to mention taking art classes, including art history, art appreciation and advanced courses in philosophy and criticism? Join art clubs for forums and artist studio tours.
Buy small, buy local. If you see a painter you like, take home a small canvas and learn all you can from it - or buy an original print by the artist or an affordable work on paper. Start small.
Here's what happened to a new collector at my gallery a while ago: He was recommended by another gallery and said he never bought art before but had $500 to spend. The gallery was showing very big paintings and he particularly liked one of the artists.
We jumped all over the place for him - we brought out some small paintings on paper and at the same time, showed him other examples of the artist's major paintings to give more background and appreciation for the importance of the work.
We arranged for the artist to deliver a nice selection of small works and the young man returned to the gallery, picked out one he especially loved and the gallery had it framed for him at cost in our customers-only framing studio.
He was very happy and we felt the importance of this sale to a first-time buyer and the artist was flattered. This story is a perfect example of a young collector getting it right.