What I'm interested to is, how to approach girls I frequently see, two or three times a week. I mean, girls I am seeing on regular basis in the university, but have never met them.
They could be interested in me as well, there is eye contact.
How do I approach in a situation like that, I already missed a couple of shots.
Whould approach be a little forced, since I've been seeing her regulary, exchanging eye contact, shurley she's interested in me.
Now should I approach following PUA guide lines with canned openers, negs, scripted routines, working to isolate, and then do comfort or close? Or should I do it swiftly, talk about anything - regular chit chat and close? What could be their reaction, remember I'm seeing them often?

Any ideas could be usefull.

If you have class with them, just ask them a question about the class. The easiest opener out there. I think if she's a girl in your class and you see her often and use a canned pickup line it could possibly seem awkward.

The whole point of canned opener is to say something when you clearly don't have anything interesting to say related to your environment. If you are in the same class you probably have a billion things to say to her to open with a lowest risk of being not interesting and/or sound fake.

Don't even think about it.