Up until now I've always used a felt tip liner, but the downside of those is that when it starts to run out you no longer get a clean line. So I decided to take the plunge and try out a real grown-up liquid liner with brush and everything. I went with YSL.
I really felt the difference in ease of application compared to the felt tip liner - this one requires a steady and sure hand. Which I don't have. So to make it easier I actually drew in a faint line with my (almost completely dry) felt tip liner first, then traced over it with the liquid liner brush. I love the effect - the line was clear, dark and defined, and didn't budge all night.