Sort out your money!
Find out any help or benefits you're entitled to, or help with housing, funding costs and get the paperwork going to claim them.
If you need to get a job then find one with hours to suit your work and study.
Money is the BIGGEST headache and you need to pay for books, food, rent, travel, electricity and maybe a TV licence.
You'll also need money for going out, drinking and clothes.
Decide on the college and course you want before you do these things.
Then read up on your course. What kind of books do they recommend? You need to really read up on your subject and the more you know the better. Students also write a thesis in their final year at uni, a copy of which is stored in the uni library. You can book out the thesises (thesi??) based around your subject so that you can do an in-depth study on some of the areas you're interested in.
You can also get yourself sorted out with a doctor and dentist either on campus or nearby. Talk to them about any medical needs you have before you start on your course, so you're all set up should you need them in a hurry.
Hope this helps and best of luck!