I heard Oprah say once that she has made a commitment to herself to not buy any clothes that do not look good on her. While she, I'm sure, has stylists and all sorts of people to help her shop, dress, and "look good" all of the time, the idea can be a money saver for all of us. It requires a little more discipline when shopping, as I have discovered.
My m.o. for years, no matter where I was shopping, was to look all day for something, become frustrated when nothing worked, and then settle at the end of the day with clothes that I wore only a few times. Oh, the money I could have saved if only I had realized the err of my ways! This is by no means saying that I look good in my clothes all of the time or that I am one of those stylish "fashion girls" as our 3 year old calls them. But, I do try to pay attention to where the hem line falls, if it has front pockets or pleats, how the material lays, what the color or pattern is, and how all of those things look on my body type and with my coloring.
If in doubt, step away from the clothes--EVEN if it is a 25 ct item at a garage sale. If it is worth it to return on another day to try it on again, you might bring whatever shoes or accessories you might use with the clothes. Do you have a friend who can be brutally honest with you? If so, bring him or her along for the ride. With fresh eyes, you might notice something that you didn't before.