What is Tightlining:
Tightlining the eyes is also know as Invisible Liner, It's push black shadow or pencil in-between the lashes. Not on the water line but in-between the lashes themselves.
Waterlining or lining your waterline is lining the "wet tissue" of the eyes or the inner rim of the eyes. It can be done with pencil, shadow (applied damp) or cream eyeliner but avoid liquid liner!!
Start on the outer edge and work inwards, Depending on how close-set or wide-set your eyes are will determines how far you work to the inner eye.
If your eyes are close-set you will want to stop short after the middle.
If wide-set bring all the way inwards and start slight inwards from the outer edge.
If you're not sure what eye shape you are check out this video: