ask about her--dont talk dirt or ask any stupid sexual questions-or how big her boobs are--see if she's going to school, if she likes her job, what she likes to do in her free time, what kind of movies she likes, if she likes indoor or outdoor activities, sports (lol yes sports), and lastly, don't go in for a kiss either; dont make it seem like you only want her there for one reason.
Make her the nicest lunch you can, and decorate it, showing her that you worked hard on that meal to please her. Sing a song to her, or tell her your true feelings for her, make her feel special and pampered. Girls love that from the ones Ive seen, and considering I'm a girl too but Im not into that x)
Just don't go all cheesy on her. Some nice music is okay, but the serenading part is a bit over the top and could make her feel very uncomfortable. Set the table nicely, and just make sure she is at ease. Save the full-on romance for something a bit more romantic than lunch. And just be yourself. Most girls can spot fake a mile away.