I like the tip about gently pulling on the eyelid while applying eyeliner - that helps out SO much, especially if you are using a liquid liner! Then you can just follow the contour of your lashline.
A trick I have learned with eyeshadow is that you can take your daytime powder and apply it with a damp brush in the evening. This makes the color more vivid and rich. So you don't have to worry about removing the makeup you had on during the day - you can just glam it up before going out at night.