When building a wardrobe, I like to focus esp. on color. I decide whether white or black best suits me (I pick black). I also pick between silver and gold (gold).
I consider my skin-tone (very ruddy) and feel warm-tones are my favorite for complementing it.
Next, I chose my favorite color to wear (red). Since red is very bold, I save it for accessories and personal items. Purple shares red's warmth without its intensity, so I prefer it for garments. Next, I think of fun coordinating colors to toss in, like mint and peach.
My color palette is not absolute, but settling on favorites has helped me limit my purchases to the best for me while maintaining cohesiveness in my colors. I only buy something if I love it, look good in it, can wear it with most of my other garments, and find it suitable for either school/work/chilling/w/e.