A couple of the ways the minimalist crowd often offers up as a way of owning/buying less clothes is to develop a uniform (a la Steve Jobs) or a capsule wardrobe (a la Project 333). Both are decent ideas and will help you achieve that goal. That said, both also are either a bit extreme (in the case of the Steve Jobs style uniform) or impracticable for most in the long run (in the case of Project 333).
The broader, and I dare say more accessible, idea behind both is the idea of developing a personal style. This is something anyone can do — likely using most if not all of what you already have. Because, in all likelihood, you already have a personal style and have not just identified it.
Identifying and settling non a personal style can be tremendously helpful when making the effort to buy less. Because once one says,”This is my personal style”, one can automatically say, “no” to anything that is not that style.
If your personal style is jeans and a t-shirt, then you can automatically avoid buying anything that is not either jeans or a t-shirt.
If you’re personal style is to dress like a Japanese Hiker, then chinos and button ups are likely something you can dismiss purchasing out of hand.
Another way to go about this is to develop a seasonal “uniform” based on what you already have. This is something I have done for the past few years. I look at what I have enough of to cover most days, how I’m feeling about it, what kinds of things I know I’m likely to do every day, etc. I even make a sketchnote of my choices for the season, thus allowing me a reference should I feel like I’ve lost my way (plus it’s fun to go back and look as what I chose the year previously).
This year, that uniform is a flannel shirt with a workshirt over that and jeans or fatigue pants on the bottom. Now, that doesn’t mean I won’t occasionally wear a sweater instead of the workshirt or a denim shirt instead of the flannel. The main reason for deciding the uniform up front is to remind myself that I already have everything I need for the coming season, have a [sensible default] that I can fall back to when I don’t know what to wear, and box out anything new I find myself wanting by remembering I already have a uniform, have enough of what I need for it, and don’t need to buy anything else.