I'm a guy thrown through a time-warp you might say, finishing up college now yet old enough to have gone through Uni, but there are reasons for that which have the college girls accept me as one of their own generation although due to my stats I obviously mix with older women too. So I can see the difference given I've got a foot in both worlds.
My advice to you (well, it's my opinion, you decide if it's advice) is as follows.
ONE: A girl has the personality equivallent of major reconstructive plastic surgery between the age of 17 (college chick) and 22 (woman - that ain't 18 trust me). Whatever you thought you knew about a girl back then won't work on her now. Same with using college come ons on any woman. Accept that it is not a new league, it's a new game. New rules. New penalties. But better prizes.
TWO: Women usually know where they are going, what they are doing, and (whether they admit it or not) if they want to have kids or at least a husband some day and so on. Think about that before you call kids "glorified rodents" or call marriage "romantic bondage". Basically, she's got a game plan, make sure you have an idea what it is, until then try not to be a totally hopeless fit.
THREE: That Tesco's cheap cider or wine. Yeah it's cheap, it's nasty, but it will get you drunk. With a girl of 17, or 22. But the difference is with a woman of 22 it won't get you laid. That kind of thing is up there with dinner at Pizzahut. With the fully-fledged woman or 'professional woman' as they are being called in this thread, don't do anything that seems like outdated currency. I mean heck, the wide polyester colllar was sexy...but in 1970.
FOUR: Never, ever, ever, ever cross business and pleasure. The river of lust/love/not sure/delete where applicable and the river of work/career/stop over/delete where applicable are two seperate streams. Remember the film Ghostbusters and the golden rule as said by Egon? "Never ever under any circumstances cross the streams! It would be bad."