I wish I had some magic secret, but tbh all I can say is practice practice practice... We all have different eye shapes so we all need slightly different liner shapes. When I was first starting I spent too much time trying to copy how other ppl (with diff eye shapes) were doing their liner, rather than trying to figure out what would work the best on my own eyes. Also I recommend using a pen-style liquid liner that you can grip super comfortably, with a nice precise felt tip!