We live in the age of brows craze. Eyebrows are getting bigger and bigger (sometimes too big) and there are many ways to achieve thick brows look. Pencils, shadows, waxes, felt tip brow liners, you name it. 
Brows coloring is one of them and although it sounds complicated and expensive it's pretty simple and not expensive at all. I color my brows from time to time, when I want to spend less time filling them in or when I want to pamper myself a bit. 
Only thing you need is brow coloring kit and some q tips. The one I use is Titania Effects Eyebrow and Eyelash dye. They have two color options Black and Brown. I bought Black because my brows are pretty dark. 
The kit comes with prepping solution, coloring gel, a brush and one q tip that I used only once and throw away, I use a new q tip for every next coloring. 
Kit also contains protective stencils you can use when you are coloring your eyelashes. I did color my eyelashes two times but I didn't notice any difference. Probably because I used less colour gel, I didn't want the gel to get in my eyes.
Now to the coloring process. It's very easy, you need to wash your face and make sure that the brows are clean and dry. First you apply a solution using a q tip. Leave it on for about one minute and then, apply a coat of color gel using a brush that is provided. 
In the instruction it says you should wash the dye off immediately, usually I leave it on for couple minutes before washing it off. 
Color is supposed to last for one week, but it stays on my brows longer, even two to three weeks. 
Important thing is to color the brows carefully, if you color outside the brow line color will stain the skin and it may end up looking messy. After three weeks you can repeat the coloring process. 
So far I've been very happy with the results of brows coloring. It didn't stain my skin and it looked natural and even. This kit has lasted me for ages, you only use a tiny bit of product while coloring. I will definitely repurchase it and try different brows coloring kits in the future as well.