The crack of dawn on day numero uno of college shouldn't be the first time you think about how to make the experience smooth and pain-free. Start considering this stuff at least a few days before your college debut.
Think Things Through
Be organized, and stay that way. Buy all the folders, pencils, textbooks, and other supplies you need at least the day before the first day of class, but keep the receipts you never know when teachers will strike a book from the syllabus at the last minute.
Set Your Sleep Schedule
Make sure to set your circadian rhythms at least a few days before class starts. While it may be tempting to party hearty with friends till dawn during those last few precious days of summer freedom, your body will thank you when it's time to wake up for class at 7 AM - or earlier. Make sure your body is on a biochemical sleep schedule that works in your favor. This means going to bed and waking up at the same time consecutively so that your body has no issues with lack of sleep on the all-important first day of class.
Trace Out Your Class Routes
Look at a map of your school, and print it out with multi-colored routes drawn in if necessary. Make sure you know what all the abbreviations for buildings stand for (ie, don't end up in the Biology building if you're supposed to be taking a Business class) ahead of time. If you get lost anyway and end up being a little late to class, don't worry too much about it any teacher worth his or her salt is forgiving of tardiness on the first day.
Eat in the Morning
Eat breakfast. I don't care if you're "not hungry," or "too nervous," or you "never eat breakfast." Eat it anyway. Something as quick and small as a banana should do the trick. Eating a little something in the morning jumpstarts your metabolism, allowing you to function on a higher level both physically and mentally. And believe you me, you want that in college, not the least on the very first day of class.
Be Early
If you can manage it, be a little early to class the first day. This will give you time to choose your preferred seat, and has the added bonus of relieving you of the pressure of walking into a classroom with twenty pairs of eyes on your every movement or a lecture hall with hundreds more. The last thing you need on an already nerve-wracking day are more superficial reasons to feel self-conscious.
Socialize and Relax!
Finally, talk to as many people as you possibly can, including fellow students, roommates, and teachers. Relax and open yourself up to the myriad of opportunities your new college experience has to offer.