Longer than it probably should be for me to explain this but I love discussing this stuff:
Whether I am thrifting or getting something brand new, it is important to me that the fabric feels good against my skin, that it either fits how I would like or I could do minor adjustments on my own, and I need to like the colours. Whilst I have had a style evolution, its more so in how I express my tastes than the contents of them. I have always liked some variety to the textures of the fabrics that I wear, I love unusual colours and fun prints, and I look for silhouettes that are sharp.
My style is basically eccentric librarian which aligns with both my tastes and my lifestyle so during the day to day I wear a lot of button downs, blazers, and heels, with a lot of the prints being stripes, tartans made out of a lot of wool, corduroy and cotton. When I am more casual there is a lot of jeans, well fitting t-shirts, flowy dresses and minis, this is when I tend to be more playful with silhouette.
I tend to wait for items to go on sale because given my tastes, the clothes that I want tend to be unpopular because people think that they would be difficult to style, or would stick out in their wardrobe. Strategically I also go to the "bargain bin" at thrift markets for the same reason lol. After the sales/bargain I will see if theres anything on my mental list that I want, and I will just try on the things that catch my eye. Then if I want accessories I look at sterling silver pieces and vintage ties and scarves. I get a lot of my shoes from my older sisters' wardrobes (and tbh a lot of other clothes, we are close like that) but if I buy them they tend to be in line with a pair I had and wore until they fell apart. Then when I have my things I try them on one last time, make sure they are within budget and get them.
My rule is no impulse buys. If I want to buy, I save and make a list with the date that I will go get the thing. I mull over it and think about why I want it in my wardrobe and then I get it. Style icons for me are Mary Quant, Myha'la, Cree Summer and Robin Williams. And I'd say the fashion journalists/bloggers/commentators/educators that I keep up with are Derek Guy, Lakyn Carlton and Cora Harrington.