Oh, I see many of you are lipstick hoarders. I am very selective when it comes to lipstick. I've given up on lipgloss or balm years ago. Just picked up 2 tubes of gloss this winter, but I am not impressed enough to purchase more. I wear only L'oreal infallible lipcolor in a few different shades (there aren't very many to begin with), and I replace as I run out.
But, my kryptonite is mascara! For some reason, I am easily fooled by the siren song of the new mascara that promises more length or super volume, and they kept accumulating - not for very long though, as the opened mascara needs to be used in about 6 months, and even less if you get an eye infection. That said, I've put a stop this a few years ago with a sly strategy. I allow myself to buy only 1 mascara (and 1 complementing eye pencil or eyeliner) at a time. The trick is I am allowed one mascara of each color.:) Currently, I have black, burgundy, and plum. So I have a bit of leeway. For example, for now I can buy a gray one if I see a great one.
As for nail polish, that was also getting a bit out of hand. I only use a very small range of colors, beiges, tans, soft pinks, red, burgundy, and sometimes dark purple. But I had many many bottles of all the barely different shades. When it came to nail polish, I did not fall for the colors, but the clever names (I am looking at you, Essie!). So solution here was to get a small box that fit probably 10 bottles of nail polish at most, and have a strict one in one out policy. If I don't want to let go of a color I already own, I am not allowed to buy a new one.
I've been doing much better with shampoos, conditioners, moisturizers and all that other stuff, since they are a bit more pricey and I made a conscious decision to use up the stuff I have a few years ago.