Liquid eyeliner is tricky to master. For the longest time I wouldn't wear it because it was so hard to apply. My lines would always be choppy and uneven. I wanted to be able to wear liquid liner though because I liked the intensity and the staying power of it. Eventually I figured out a way to apply it more easily.
First I would apply a thin line using my pencil liner like normal. I used this as my guideline. Then I traced over it with liquid liner in short strokes. It was easier to see where my line should go and how thick it should be. It also looked smoother since the pencil liner acted as a base.
After I got the hang of it, I stopped needing to use the pencil liner altogether and my eyeliner came out flawless (most of the time!).