I have a habit of focusing on the eyes while looking at one's face and focusing on the face before looking at the other parts (unless I'm walking in a street and someone's holding something in his/her hand; putting hand in a pocket, etc.). Sometimes friends go all "look at that girl". I look at her face and respond with a "meh" prior realizing they were referring to her enormous bosoms.
One friend always announces that I'm starring, so when we interact I make it a point to stare. Like turn my head, look, look, look, slowly answer the question. He then goes all "Staring mee lololol :3". I find it amusing, which stimulates me to continue.
A few days ago I was taking my nightly walk in this passage, surrounded by trees and no light sources whatsoever. Two thuggish looking guys (leather jackets and everything), shorter than me, were walking to my direction. I flicked my knife in the pocket just to make a click sound and looked into one's, than the other's eyes the whole time. They were starting back at me, which made it even more interesting. I did, however, feel a bit uncomfortable when they ended up behind my back as there were no shadows (due to no light sources) on the ground and I was listening to music, coming from my earphones. Still, it went well.
I usually focus on the eyes and the forehead when making eye contact rather than the lower triangle, i.e. eyes and lips, though I try to maintain the other approach as well.