During conversation, maintain eye contact for the most part. Look deep into one of her eyes and nod as she blabs. Nodding and saying "yeah, mmhmm" will score you big points b/c she thinks you are an active listener.
During the "triangular gaze" (you both look into each others' eyes longingly), go for the kiss test. Brush her hair from her face. If she goes with the flow, kiss her.
Otherwise, don't concern yourself about it too much. Practice maintaining eye-contact and nodding during every conversation you have, and you'll be programmed to do it with HBs.
I try to make eye-contact with everyone I pass. If you're smiling, you'll be surprised at how many return-smiles and "Hi's" you get. If you look away as soon as you make eye-contact with an HB, it makes you look weak. You don't have to stare, just hold EC for a second or two. If you look into her eyes and then she shifts her focus to your eyes, don't immediately divert you glance away from her. Don't let her swat you down! Just give her that look that says, "Yeah, I'm lookin' at you and I like what I see, toots

"
Don't wear a perma-smile either. If you're already grinning like an idiot when you make EC with her, it doesn't say much.
If you have your normal game-face on and then gently smile (mona-lisa style) when you see her, it tells her that you dig her at least a little.