Having trouble getting things kickstarted. I need a refresher or something!

I've been seeing this girl for a little while and I've decided I really like her and would like to start a serious relationship with her. The problem is, she's hard to read and I've been out of the game for quite a while. My last relationship was pretty stable (up until the end) and we ere living together for some time. I think she's interested in a serious relationship but I'm not certain. On one hand, she says things that make it seem so (on Thanksgiving, she told me she was thankful for me, for example), but on the other, she's stood me up on more than one occasion and sometimes ignores me completely. In her defense, she does have three jobs, but technically so do I. When we actually do manage to get together it's great, but that happens less than once a week it seems.

Again, I trend towards actual in depth relationships more than just a flavor of the month. I also must re-iterate: I'm badly out of practice. I wouldn't even flirt while I was with my last girlfriend; she was rather insecure and her fiance had cheated on her just before she met me. My options are to either (1) Take it one day at a time, continuing what I'm doing now and struggle to be patient, or (2) Speed things along a bit, although I'm not certain how to go about doing this yet.

Any advice? I really don't want to mess this one up.