Tips for a fresh grad starting my first 'real' job?

I’m pretty much finished my bachlors degree and was lucky enough to find my first real ‘full-time job’ doing working on internet projects for a small but reputable marketing/PR firm.

I’ve actually been working for a decade now, first at computer store then just as a freelance computer administrator. But that was all part-time and a lot less structured and very self-directed. i.e. I’m one of those Gen Y slackers that gets up at 3PM and has a burrito for breakfast reads some blog, and calls it a day.

I’m excited but a little nervous about this new ‘adult’ job so I’d appreciate any tips, advice, and stories as a really enjoy those stuff I wish I knew when I was 21 kind of questions and would like the same kinda input about the work-life-post-college transition.