Whenever I purchased her clothes, I bought pinks and purples (her favorite) and chocolates and blacks. These were her main colors; anything else in a different color had to coordinate or be of a similar shade strength as the main colors.
Does this make sense? I wish I knew the terminology to describe this. I intuitively know this, perhaps you do, too. If not, google to find blogs or websites that explain color wheels or ask a well-dressed friend what colors best suit you.
You can do this for husbands, too. Er, I mean adults. (wink wink) Buying from a handful of colors in similar shades or tones helps eliminate the "need" to buy a pair of pants to go with "that one shirt" that doesn't go with anything else
For myself, I prefer browns, reds, and black. Splashes of hot pink and teal are my second-string color choices, which also coordinate well with my main colors.
For my toddler daughter, I choose a base wardrobe of pink and blues (purple obviously being a blend of the two) when I purchase clothes for her. This doesn't mean that she (or you) will get stuck in a color rut. Take for example my daughter's clothes in the photo.
Some other colors she can also use (such as in accompanying hat, scarf, belt or shoes) are black, dark brown, denim, whites, creams, and certain reds or pinks. And of course, I can get her a dress in any other color since it will most likely not be paired up with anything else in the closet.
I admit this tip is harder to apply with hand-me-downs that can come in a rainbow of colors, which we receive also, but it is not impossible. But definitely, when you're going to put a dollar toward your wardrobe, go for something that you will be able to match or mix well with most of your clothes. You will save hard-earned money, shopping time, and dressing frustration in the short and long run.