Yep I agree - if you're seeing her a lot anyways then texting is a bit of a backwards step until you have progressed things a little further and you can use texts to esculate what you've started. I was in the position of being the helpful, friendly guy to some hot girls for a few years during college/uni because they knew they could use me and not need to give anything back. How things have changed! lol Make sure she knows that yes, you get on well, but that doesn't mean you're going to carry on giving up your time with nothing in return. Maybe something along the lines of next time you help her with work...'I am going to whatever-bar on Friday - I take it you're going to come buy me a couple beers for helping you out with all your work' Statement not question. Don't let her say maybe etc - or add 'Is Friday or Staurday better for you?' again - you're being dominant and telling her she is coming whilst allowing her to think she has a say in it by choosing what day/time/pub etc

This is a big thing for me as I was used for years simply because I was too geeky or stupid not to have some backone and tell someone who was screwing me to fuck off. And so it is a bit if a mission for me to change myself around - and help others in that position too - so let us know how it goes buddy ;-)