I always use eyeliner under my lower lashes, but not on the water line. I also put liner above upper lid, too. Revlon just came out with a new gel liner with the brush that comes out of the lid. Really stays on and does not flake. Do not use too much because it is hard to get off, but it is worth it.

I usually use a silver or white liner on the bottom to make my eyes appear bigger. If i do use black for a smoky look, i only line the bottom half or 2/3 of the lower eyelid and top.

It's quite common to apply eyeliner on the waterline (the inner part of lower eye lid). Make sure that the eyeliner is 1) waterproof, and 2) optomologist tested or safe for contact lenses (that way it's less likely to irritate the eye in general). MOST eyeliners made today are much safer to use than formulas produced decades ago because of how frequent women apply the liner along the waterline, so many liners can be used safely. 

One thing I like to do when I'm applying eyeliner is that I like to pencil it in a little heavier on the lash line (so that a little falls in between the lashes. Then I use a flat liner brush to smudge underneath as close to the lower lash line if I want to do a more dramatic effect (looks great on smokey eyes--less likely to appear like raccoon eyes too). 

Yes, I do line my lower line everytime I go out. It emphasizes my eyes and give it a more dramatic look. I used to do it ever since I was 16, the time my classmate taught me how. But I don't line my waterline anymore, as it gave me red and itchy eyes, and I do warn all women out there that there was a study saying that lining the waterline can infect the eyes.

Makeup is really about what you like and what makes you feel good! For example, I personaly don't like to apply eyeliner to my waterline as I find it uncomfortable and that it gets into my eye. I realy like to apply a thin line using eye shadow and a precision eyeliner brush. It is also a must for a smokey eye. Just play around and have fun with it until you find what you like!

I always line my lower lid.Without it i barely look like i have eyes (at least in my opinion). I have been doing this for almost 50 years. I usually use dark brown liner, have for almost 50 years. I have very fair skin, dark brown hair, and hazel eyes. Occasionally i use a dark color (purple, teal, olive) to spark up an outfit, for performances, or when i am in the mood.

I rarely put stuff in my waterline because my eyes are sensitive - it usually makes my eyes burn, tear, and turn red, not generally an attrative look

Tried it once but I have big eyeballs and it went bad.. (raccoon eyes). So, I prefer it on the upper lid for dramatic look! 

I do, I use it on my water line, top and bottom. MAC makes a great eyeliner for this, it stays put for hours, doesn't run or wear off, I love it. And they say you shouldn't do it the older you get, but it makes me look so much better with it. And sometimes I'll take another color and use it under my lashes, so I got 2 colors going on, and it really makes my eyes pop, and good for the smoky look. Hope this helped some