It is a great idea to start your business, when you are in school. The earlier you start the earlier you are going to make it. Having said that starting new business is tough, it gets tougher as you get older, because you have lot more responsibilities to fulfill, because you will get into other roles as well, husband, father, responsible head of the family etc.
The best place to start is to identify problems, any problem that people are having in general, it could be a consumer problem or it could be a B2B problem, unfortunately you being a student, you might not have a whole lot of industry expertise, unless you worked part time somewhere while you were a student and learnt some business along the side, because many consumer problems are solved by many technology experts, that have generic technology expertise, the consumer problems don't need a specific industry expertise other than the expertise to develop a solution, where as there are plenty of problems that are still there in the B2B world. And to learn about that problems, you need to spend time in that industry, you need to spend time working alongside users that have the problem, talk to decision makers that would buy that solution, that would even take time to look at the solution you are providing, so that is tough. But if there is any specific area that you might be interested, it might be a good idea to take a look at that space and spend some time.
Once you learn about an existing problem, then thoroughly understand the problem, why the users are having that problem, why no one attempted to solve it, what solutions were tried before and why they failed? Look at every possible angle of the problem and just understand the problem, how the problem originated? What led to this problem? What are some of the things that are changing around this problem, it could be technology or legal things, a new law might have been passed or an industry trend is changing, or a major manufacturer that was supporting the product decided not to support it etc
Once you understand the problem, then come up with a solution, a solution that is easy for end users to adapt to, they can easily transition into, the young users will also easily transition into etc.
Then deploy that solution, then get constant feedback from your users and keep on improving that solution.
Also check out my book Puga Sankara's Supply Chain Blog - that is a must read before spending Hundreds & Thousands of $$$ on your MBA or Masters Degree to get the best ROI or before starting your Entrepreneurial journey.