I personally suggest investing a little more money and getting a pen. Pens will come with sterilized cartridges and the needles are fresh everytime. I have used rollers before, but the last time was when I used a freshly "disinfected" roller and I broke out in all these little pus boils. Also some rollers, like the ones on amazon, are not actual needles but little metal cones. In my opinion, rollers can really mess you up. There are a lot of videos on YouTube about derma pens you can check out. I think I spent less than $200 on mine but I cannot quite recall at the moment.

Go to a dermatologist cuz you can seriously fuck up your skin

seems rolling can be extremely beneficial. you can do this anywhere on your body. there are different rollers for different body parts and different techniques to use. do your research before hand. utmost priority is to sanitize the roller every time. got mine off ebay and they were fairly cheap. good luck! :)