Dont buy things other people tell you to love. The art world is a curious place and youre told to love Damien Hirsts congealed pig fetus, but that doesnt necessarily mean youre going to love it when you get it in your living room.
Dont overthink things. You should have an immediate, personal response to any art you buy. Trust your gut.
Dont be driven by measurements. Just because something fits over your mantel doesnt mean you should buy it. Buy what you love and create a space for it. Art, like books, always makes the most of a space.
Dont think of it as staying in one place. Famed collector Dominique de Menil regularly moved her art to different areas of her homes. When you move pieces around, you dont take their characteristics for granted, and they take on a different viewing power.
Dont limit yourself to gallery shopping. I buy art at auctions much more than I do galleries. Its the best way to get art at the current market rate.