Matthew L. Tuck, J.D., M.B.A.
It's also a complicated question. In general, to have a successful business (big or small), you need several things.
1. A good concept for the business. You have to have a product or service that a lot of people want and that you can produce and sell at a profit. There is a reason that you see a McDonald's, Walgreens or 7-11 on almost every corner. They are good business concepts. Lots of people want what they have, are willing to buy it, and the owners can provide what they sell at a profit. If you have something no one wants, you can't sell it at a profit so you don't have a business. Similarly, if you have a great idea that everyone wants, but it costs you $10 to make and people will only pay $1 for it, you also don't have a business.
2. You need to work hard. Owning a business is a lot of work. It's not like a regular job where you punch in at 9 a.m. and leave at 5 p.m. and someone in charge worries about rent, insurance, health care, customers, sales, utilities, marketing and law suits. You have to wear all those hats (at least at first--eventually you can hire people to do the things you can't or don't want to do).
3. Capital. At some point you will need money to grow your business. You can start a small website building business in your parent's basement, but you can't grow it very big.
4. Must be Able to Learn from Mistakes and Adapt. The environment and your business will constantly change. You must be able to learn and adapt. You don't need to have a business degree (but it helps). You can learn business from the ground up but be prepared to make a lot of mistakes. Learn from them and never give up. Read everything you can get your hands on about the industry(s) you want to get into.
5. Must have a Competitive Advantage. Your business needs to be just a little bit better than your competition (if there is no competition, you probably don't have a great business idea. McDonalds has TONS of competition--they're just a little bit better). You need to be more efficient, have a unique product or service, or have higher quality than the competition. Try not to compete on having the lowest price.
6. Must Love What you Do. I would also add (from personal experience) that you should pick something you love to do. Don't chose a business because it's glamorous or you think it will pay you a lot of money. It really helps you success if you love what you do.
Some other things I would recommend.
Make sure you have a written business plan. Plan everything out like, how you'll get customers, how much everything costs. If you need an office or store, find out how much that will cost. Unless you can do everything in the business yourself (selling, answering phones, cleaning the floors, accounting, marketing, unloading the trucks, computers, insurance, etc.--And you can't do it all yourself), you will , need help. Plan for employees or contractors to do the work you don't know how to do or don't want to do.
Learn as much as you can about the business you want to get into. Get a job or an internship with someone else in the business to see if you like it. Observe what they do well and what they don't do well. Are the employees happy? If not, why not? Can that be fixed in your company? Are the customers happy? If not, why not and
I take it from the tags attached to your question that you like sports and may be interested sports management. If you love sports, that's a good start. But it's not enough. Being a sports agent or managing a baseball stadium is less about sports and more about other talents you must have. You need to be a great networker and be good with people. If you want to work with famous athletes that can be hard. It's very competitive and the people who become successful sports agent have worked like crazy for a long time to get there. They tend to be the best of the best. Many of them also are attorneys or have business degrees. You need to understand contracts, relationships, business, and people to succeed. You need to understand business.
One thing I would also recommend (from personal experience) is to take an accounting class or two. If you don't understand how accounting works, it's hard to manage your business properly. Business degree is also a great start and will give you a great foundation to build on. School is also a great way to network, get internships with companies you admire and that are in your field, and to see if you really like the field you've chosen (you may not like it--just be honest with yourself). Never go into a field you don't love because you think it will get you money or fame or expensive cars. Find what you love and if you work hard at it, the other stuff you want will come.
And lastly, don't listen to people that tell you can't do it or that you're not good enough. You are good enough. If those people could do it, they would be. Ignore the haters. You may fail the first time and the second time. But learn from it and don't make the same mistakes again. The guy who wins is the one who gets knocked down 7 times but gets up 8 times. Believe in yourself.
Hope this helps.
Matthew L. recommends the following next steps: