This year I did some shopping at TheRealReal. The temptation for buying with sales goggles is very high on that site, because everything is good quality and significantly discounted. The trick I learned was to mentally add $100 to the list price and ask myself if I would still be so eager to purchase something if it was offered at $160 instead of $60. And if I wouldn't buy it at $160, would I be willing to stalk it online for a couple of months to see if the price went down? If not, then it obviously isn't important to buy it.
Alternatively, for items on TheRealReal like $30-40 designer cotton t-shirts, I asked myself if I really liked it 3 or 4 times as much as $10 shirt from Target, Talbots etc... I bought a number of great items online at that site that were "final sale/not returnable" by means of careful thinking about all this.
Additionally, I assessed my existing closet for personal trend-proofing. I
and discovered that I don't get tired of crisp patterns, whereas I do get tired of more blended and soft muted colored prints. Alternatively, I do get tired of contrast piping/stitching and prefer basics to not have a second color detail on trim for a belt, blazer, handbag etc.... Another pitfall for me, discerned in retrospective closet analysis, is buying something because I like the color and the color isn't readily available elsewhere for a given retail season. For example, a few years back, I was keen to buy a cobalt blouse and by the time I found one I ignored the fact that I don't like the oversized style for myself.
And lastly, yesterday I wrote out a detailed shopping checklist for 2018. I usually just have an annual budget and a vague mental list. But there is a difference between thinking: "I need to leave room in the budget for a few pairs of shoes" and thinking through to decide to prioritize refreshing specific sandals, flats and athletic shoes for a total of seven pairs. The latter realization I am certain will more successfully curb the spending impulse when I think: "this is such a great versatile dress at a great price. " I am more conscious of the fact that I have sufficient day and party dresses, whereas my shoes are starting to get too flimsy which is bad for my feet, knees, hips etc... To clarify further: I feel like a complete shopping list also helps me to think in capsule-budget blocks. For example, this fall I decided that it was more important to get a longer spring/fall coat and two warm woolen blazers than to refresh my sweater capsule. I'm spending more time shaving pills off of sweaters than I would normally like to do, but it helps me to see that this is a good tradeoff for winter 2017-2018.