Some classes are going to demand more professionalism from you. You can't just show up in jeans and expect the professor to take you seriously. You need to at least go business casual here. Instead of buying a ton of jeans and tees, consider getting a few pairs of slacks and upgraded tees. You can even be cute, colorful and comfortable. (I used to have a pair of dress pants made from a thick jersey. They felt like sweat pants, looked like suit pants). It's the same amount of effort as putting on jeans and a tee, and your demanding professor will answer your questions and give you the respect you showed for the class.
If you're going to get up in front of the class to present information, put effort into both the speech and your appearance. You don't have to wear a suit. In fact, a chic and simple blazer is more than enough to spruce up any speech day look. If you need to dress casual for the day, you can add a blazer to pants and tee. It can also top off a simple jersey dress (especially if you're going from class to coffee with that cute guy who sits in the back row).
The career fair may be set up in the student center inviting your to browse as you flit from class to class, but you are meeting recruiters and potential employers/internship supervisors so dress to impress. This is a business casual or better setting. Try a simple skirt and blouse combo, bring along a jacket to dress up the look if need be. I love a classic straight skirt or pencil skirt. A lot of them are being made in thick jersey materials that move easily and pack well if you end up traveling to a conference.
Sure. You're a freshman. You're just trying to get a job at the coffee shop on campus. You're not looking to make partner at the firm or even get your first "real" job, but you can still look better than most of the other applicants. I got a cushy job in college filing paper and eating all the treats people brought to the business office. I interviewed in pants and a blouse. Later, after changing back into jeans and a tee, I ran into my interviewer in the cafeteria. When he hired me, he commented on the fact that I showed up in professional attire even though I didn't always dress like that. No one else had dressed up. I got the job. Get an edge where you can. Buy great separates that can look like a suit put together and mix and match well with the rest of your professional clothes.
All of the looks above have been created using the set of clothes pictured below (plus a bonus grey dress pictured first. It is made of sweatshirt material, but it's a dress. You can't beat that). I picked comfy fabrics and affordable pieces. Every piece is less than $35. I included two dresses, two pairs of pants, two skirts, two jackets and four tops (because no one wants to do laundry all the time). The whole wardrobe of 12 items (with countless combos) costs just under $235. Click through the slideshow to see each item individually.
Pictured: Grey sweatshirt dress, Dorothy Perkins $28; Jersey faux-wrap dress, Old Navy $17; Graphic tuxedo pant, jcpenny $14; Classic pant, jcpenny $14; Flounce pencil skirt, The Limited $20; Blue pencil skirt, Old Navy $20; Terry fleece blazer, Old Navy $35; Blue boyfriend jacket, Target $30; Button front blouse, jcpenny $12; Orange cowl top, jcpenny $15; Dot top, Dorothy Perkins $12; Crochet tee, Loft $17