My top tips for eyeliner are:

• draw the shape on first using a kohl pencil, it's a lot easier than going in straight away with liquid eyeliner
• start small with the wing, you can always add but it's harder to take away!
• use q tips on dry liquid liner to clear up mess, it'll come off easier than trying to clean up wet liner
• keep your pencils sharp!
• tightlining your upper lid has more of an effect than you will ever think
• the NARS High-Pigment Longwear Eyeliner combines the best bits of a kohl and a liqid liner