I used to tweeze them until I lost my favourite pair and let them grow out. I had my eyebrows kind of "porn star" looking (aka, really thin and tacky IMO). When I realized two months went by and my face looked a lot...prettier?...I didn't bother with the tweezers ever again. I kind of have a natural arch, and they aren't super duper hairy or anything, so it's nice to have one less thing to groom.