I should do it more often. A lot of times I buy things that end up not fitting or I wear once because I didn't completely love it. Recently I've been returning stuff instead of stashing it away in my closet, and I realize now why some people fall into the chronic "buy it, return it" cycle.
I'm really trying more or less to NOT buy things at all unless I can't live without them. Which is hard for me, since I tend to think I can't live without any of the things that I buy.
It's not such a bad mantra though. You can apply it to anything. Don't get a haircut you can't live with forever. Don't buy the shoes if you don't know what you'll wear them with.
If you know you love something and it makes you feel and look happy, then go for it.