I start by filling my brows in first so I can follow the angle of the brows. I always start the line at the outer corner of the lash line drawing up in an angle towards the end of the brow. Then drawing an upside down V shape back down towards the lash line. Finishing the V off centre on the lash line so it is at an angle to the brow arch. Then I finish by drawing a thinner line across the rest of the lash line. Sometimes I go over it if it needs it. Another tip is to rest your below on a table whilst applying the liner.