GPS where your classes are on campus and walk to them a day or two before the first day of class. Half of your class will probably be late on the first day so you want to get ahead of the game and know where your classes are! This will also help you get to know the campus a bit before you're rushing around and unable to actually pay attention to your surroundings. You should also try doing this with a friend so you can have a good idea of where some other buildings are and maybe you can find a common meeting ground for in between classes!
If you'll be living in a dorm this year, make sure you buy a microwave! I cannot express just how important it is to be able to cook quick foods in your dorm because you WILL be running late some time during the semester and you'll need some food to stay sane all day. Microwaves are usually around $20-$35, and are cheaper during this time of the year when stores are having their "back to school" deals.
Make sure you purchase a meal plan because you never know when you'll be running low on money and you need to grab a bite around campus. Having a meal plan is essential when you're living in a dorm since you won't have immediate access to a kitchen and groceries usually aren't in the budget for freshmen!
The first week of the semester is syllabus week. This is most definitely going to be the most boring week of class, but DO NOT skip it because your teachers are going to be giving you valuable information! They will be telling you when the tests and quizzes are, telling you their office hours and where their office is located, and other useful info. I strongly suggest that you actually look through the syllabus and write down when tests, quizzes, and off-days are. Especially if you're prone to skipping classes here and there, it will be useful to know when you can or can't just blow off class.
Choose your skip days wisely! Of course most of us are going to skip a few days of class if we're sick, can't seem to get out of bed, had a long night, or might want to take a 3 day weekend vacation mid-semester. However, you only have so many days that you are allowed to miss class before it starts to negatively affect your grade. In most cases (for ASU and NAU at least), you are only allowed to miss 2 weeks of class and then your grade will go down if you miss more days without it being a university excused absence. If you have a Tuesday-Thursday class, then this means you can miss 4 days of that class. If you have a Monday-Wednesday-Friday class, then you can miss 6 days of that class.
All work and no play is NOT a good idea in college, it will only put you on a fast track to hating your college experience and being unhappy these next four years. Although you may think college is going to be the most serious and stressful time of your young life, it will be in your absolute best interest to make friends and have some fun while you're here; it will make your college experience much more memorable. However, with that said, don't forget about the work part of college!
Although skipping class and microwaves aren't the main focuses of starting college, they will soon be huge parts of your lives and you'll have to start forcing yourself out of bed to make it to class! ...and for the love of all things holy, DO NOT CHOOSE AN 8 AM CLASS!