While separating my wants and needs I find it helpful to really introspect on my taste and find out what I actually want enough to get. For example, I am really into fashion and enjoy buying and making new clothing, but usually have a pretty low budget, and am very wary of the harm overconsumption and fast fashion can do to the environment. Because of this before I shop online I make a list of the type of item I'd like to get so I don't get distracted and land on something that I don't actually want. After I decide on something I usually let it sit in my cart for a few days so I can find what I'd like to wear with it, and make sure I really want it. It helps me cut down on consumption and really apriciate it when I do get new clothes.

I really like your solution of letting things sit in your cart for a while and thinking of what to wear with them before you buy them. It's important to give yourself some time to think about your purchases to limit impulse buying, and thinking about how it will go together with pieces you already have also helps your wardrobe fit together better.