Starting an "IT Co-op" with minimal experience ( 1 semester on school help desk ) is a big step. Factors that will assist or hinder your chance of success will be:
1.Find out as much about your target market as you possibly can, you need to know what services you can provide that potential customers can be reasonably be expected to want to pay for.
2. The caliber and experience of others who may join the co-op, you need people with skills that compliment the skills of the others in the co-op. You don't want a situation where you end up in direct competition with yourselves for available work. Working alongside the more experienced and an open mind can be beneficial to gaining knowledge and experience.
3. a factor to consider is how you are going to finance the initial start up period when you may have minimal income but many expenses as part of getting the co-op out there into your market. There have been many good business idea's that have failed due to lack of finance. Not having to rely on the co-op to provide an income to live on may make establishment easier.
4. Do your homework. find as much as you can about the business side of things, understand basic accounting and what records you are required to keep for tax purposed etc. Keep in the back of your mind at all times when the money comes in, it's not all yours, the tax man will want their cut as well.
5. Don't be scared of putting in the effort to learn as much as you can about as many different aspects of technology as you can. Learn to look at each problem you are presented with with no preconceived point of view. Books, internet etc if you take the time and put in the effort can be great tools, as it is highly unlikely you will come across problems that have not been encountered and solved by others.
6. To have any chance of success you will probably be required to work harder than you have ever needed to before, you will need to enjoy this type of work as in the beginning you will be working more for love than the money.
7. Understanding the concept of a "dress code " is a good concept , the first step towards becoming a professional outfit is to present yourself as a pro, but it is important to back this up with true professional service.
Good luck ,as if you go with this you will need all the luck you can get. There will be depressing times along with the good, try not to let them get you down. If in the end you meet with success or failure it will still be a positive experience, You are still young so the things you will gain from trying this in the long run will all be positive, eg. knowledge strength of character, work ethic. Give it your best shot, but don't be afraid to walk away if it does not work out, taking out the positives before being dragged down too far and then you will be able to take what you learn into something else.