Qualification can accomplish several things, like build compliance, DHV, break rapport, and categorization of girls. I'm going to talk about the last point, as I think it's one of the most important uses of qualification. You want to find out what kind of relationship you can have with this girl (e.g., not worth seducing, one night stand, FWB, open relationship, LTR). In order to do that, you need to create criteria for each of these. Start off by qualifying a girl on the lowest level qualities (e.g., one night stand) then move up as she continues to meet progressively more stringent criteria.

The things you qualify her on are based on the qualities, traits, values, beliefs, and behaviors for different categories. For example, a value I desire in a LTR girl is maturity. Here's one conversation that's I've had:

Me: Have you ever had a disagreement with a roommate before?

Her: Ya, sometimes my old roommate would play music very loud.

Me: What did you do?

Her: I'd turned my stereo up real loud to show her how annoying it was.

So, she's probably not LTR material in my books based on her passive-aggressive conflict resolution style (lack of maturity), but may be more suitable for another type of relationship, like FWBs. Of course, this is not a typical type of qualification you'd likely have in a club or bar. For those scenes, you probably want to stick to lower level, less intensive qualifications (e.g., What makes you a good friend? What motivates you to get up in the morning? What do you have going for you besides your looks?).

Now, to tie it into how qualification can be used to build attraction and comfort. Whenever a girl passes a qualification (e.g., you find out she volunteers at a local pet shelter), this is an opportunity to communicate interest in her (e.g., "Hey, I really admire that you're so caring to animals."). The reason why this enhances her attraction for you is because she knows you like her for reasons besides her looks. Women want to to feel special. Biologically, they want to know that you won't leave her after sex or when her looks start to fade. That is why you should communicate what you find special about her after qualification.

In summary, you qualify her based on criteria you set for each relationship type. Those criteria are the values (what's important to her), behaviors (how does she treat you), and traits (what kind of person is she) that are important for your relationships.

EDIT 1: Thanks for your all input. However, there seems to be some confusion. Perhaps I should have titled this "How to Use Qualification to Build Successful Relationships". Many are seeing this through the lens of whether this advice would be useful in the initial pick up. You can still do that, you just need to calibrate your qualification (and its purpose) to the situation you're in. I try to address the issue of relationship management (more of my expertise) in general and how you can use qualification to further enhance attraction and comfort at the later stages of a relationship.