Understand What Works For Her Might Not Work For You
The first port of call for most people when choosing beauty products is a personal recommendation. The problem is that everyone's skin and hair is different, and what works for one person may not work for another. Sure, we can all swatch an eyeshadow and work out if it's pigmented enough. But the moisturiser that works wonders on your friend's dry skin might be useless on your combination.
I used a lot of stuff in my early 20s that was recommended by people I trusted but just wasn't right for me. I still ask for (and give) recommendations all the time, but always with the caveat that personal preference is a huge part of choosing beauty products, and we all want different things. When it comes to your own skin, it's down to educated choices followed by plenty of trial and error.