(Really, go read. I'll wait.)
In the comments, Snigdha asked about contacts and eye liner: "Here's a request from a person with minimum experience in makeup -- but I do wear kohl once in a while: a post on eye makeup (especially liner) for people using contact lenses. Failed quite a few times. Either eye hurts or makeup smudges."
We can do that!
I'm a contact lens wearer; I am also, in my 40s, beginning to experience the pre-menopausal Dry Eye Syndrome (I can't be the only one with that going on, can I?). On a typical day, I wear my contacts for an average of 16 hours, which is substantially more than the eight hours my eye doctor recommends. But since I wear daily disposables, it seems to work out fine. Except for the part about my eyes getting itchy at the end of the day.
All of that wreaks havoc on my eye makeup, of course.
Having said all that, though, let me also say that I wear eye liner on a pretty regular basis, and I don't have any trouble with it smearing or itching. What's the secret?
Keep eye cream to a minimum. I'm a big believer in eye cream; use it early and often and you'll be looking good well into your golden years. But while there's nothing wrong with layering on the eye cream at night, go light during the day -- too much eye cream can cause liner and mascara to run. For day, pat on the tiniest bit of eye cream (using your ring finger) from the outside corner to the inside. Give it five or six minutes to soak in before you start your eye makeup.
Choose a long-wearing pencil liner, rather than a gel or liquid. Pencils tend to be easier on the skin; a long-wearing pencil shouldn't smudge. I like Nars basic eyeliner pencil; it lasts all day without smearing and doesn't make my eyes itchy. Available in 12 colors for $20.
Sharpen your liner before every use. If your skin or eyes are really sensitive, cleaning off the outer layer of your pencil before you line your eyes removes bacteria and other irritants that might have settled on the pencil. Having a sharp tip also means that you'll use less liner because you'll be able to get a clean sharp line on the first try, which lowers the chance of smudging.
Line only the outside edge of the eye, not the inner rim of the lid. In other words, line your eyes so that your lashes are between the liner and the white of your eye. Fashion magazines constantly tout the benefits of lining the inner rim, but this is just plain risky, and especially so if you wear contacts or have sensitive eyes.
Other sensitive eye options: Almay's Blendable Eye Pencil ($7), Clinique's Khol Shaper for Eyes ($15.50), and Neutrogena's Nourishing Eye Liner ($8). The Neutrogena liner is actually a gel, not a pencil, but it's a lightweight, non-irritating formula that lasts all day.