The main ways to raise money are borrowing it from a friend, a family member, or a commercial lender, or selling ownership interests (equity) in your business. There's no hard and fast rule about the best way to raise money -- you'll have to evaluate your situation and decide what kind of loan or investment you're willing to take. (Also, of course, whoever loans or gives you money will have some input, too.)
If you'll be going beyond family and friends for loans or equity investments, you'll need a business plan. For more information, see Business Plan FAQ.