Color management methods

Hi. I originally never wore sleeveless tops because of underarm discoloration, and if I wore short sleeves and it looked like my armpits might show, I would always wear a jacket over them. However, seeing more people wearing sleeveless tops lately, I’ve started wanting to wear them too...

I feel like I should finally start the skincare routine I've been avoiding, and I'm curious about what products help with discoloration! There are so many advertised products, but I hesitate to buy them because I'm worried they might all be exaggerated claims. Also, when I look into products people rave about, sometimes they have almost no brightening effect... I really want to know what products have actually worked for me!!!