Seem Interested In Her, Not Just Having Sex
Even if you're looking to have a one-night stand, there's something to be said for subtlety. For the record, mentioning breakfast at any point in the conversation if it's past 11 a.m. is not subtle.
She should never feel like you see her as a means to an end for your penis, or assume your only aim is to get laid (even if it is).
Even if she's down for causal sex, she won't want to feel like she's merely an outlet for your desire. Convince her otherwise by not overtly ogling her (as mentioned earlier) and seeming genuinely engaged in the conversation. Asking questions about her that don't revolve around the color of her panties is also helpful.