I have some disposable income every month that I usually use for clothes/beauty purchases- I don't spend a lot on socialising these days and most of the gallivanting that I do is done with DH which we tend to pay from the disposable we have after essentials in our joint account.
If I've bought something reasonably dear (ie not primark type prices) and not ended up loving it or wearing it as much as I thought I would and it will sell for a decent price (Boden, etc) I would ebay it and probably use the money for other clothes.
If I'm buying online, I always try to find a discount code ( there is usually one about) and don't buy clothes from shops that frequently have sales until their discounts are on (White stuff, fat face, M&S, Wallis are the big offenders)
Sometimes if I'm buying clothes for a new season (winter/summer) I put it on my credit card and pay off over 2 months 
Clothes are my weakness, and I do find myself buying stuff most months but I'm happy to spend less on alcohol etc and be frugal with other things.
I used to spend money I didn't have on 'stuff' but I'm much more cautious now and return stuff quickly if I change my mind about it and try to buy more classic clothes that all go together more. I do have some debts (which I'm steadily chipping away at) and would like to be saving more so I am trying to cut back on clothes purchases.