Word of Advice: Make an effort to wear a certain amount of garments you've never put on before (except for the fitting room that is) each week. You could, eg plan to wear at least two new pieces each week and if you end up with stuff you still haven't worn at the end of the season, it's time to let it go.
Word of Advice: Ask yourself if you don't already own one (or more) similar piece(s) of clothing. Chances are you already have half a dozen variations of said item lurking in your wardrobe anyway. So if it's not a basic item which you wear on a day-to-day basis (think underwear) chances are you merely want it, but not really need it. Buying something just because it's cheap and cute is the fastest way to turn the 80/20 rule into the 90/10 rule and that's not where you want to be headed!
Word of Advice: Purge purge purge. If you haven't worn it in the past two years, wear it, and if you end up not wearing it by the end of the season, out it goes. If it doesn't fit anymore, toss it out. You'll never loose those pesky five pounds anyway, trust me. Donate it or sell it and next time, spend your money more wisely.
Are you living by the 80/20 rule? Want to break that buying-but-never-wearing circle? What do you think of my suggestions? Anything you'd like to add as additional tip?