I was shown this tip by a wonderful friend and it is so easy! I am the worst at eyeliner and if I can do it anyone can!
Start by doing a normal eye outline, I like the Avon Glimmerstick in Cosmic Brown, but tbh any eyeliner which works for you is fine.
Take a Kirby grip/bobby pin/hair clip. You know the ones, with the little V at the end.
Then colour the bobby pin V with a felt tip style eyeliner, again I like the Avon one but any will do. Then press the V on to the corner of your eye so the straight part goes up from your bottom eyelid line and the top of the V goes towards the upper eyelid line.
Check out my video here for the full tutorial!