I looked pretty heavily into getting a business loan to acquire my business. It's definitely not a piece of cake. You have to put together a convincing financial strategy for your business.
You basically have to prove that you will be able to pay the loan back with your business. Unless you have some sort of collateral to back up the loan.
You'll need numbers, specifics, suspected profit, current customer base (if any at all), factual evidence that will convince them this will work for you. Otherwise, they simply won't lend the money. In todays economy...I'm guessing they aren't throwing these loans out like candy. But, I could be wrong.
I'm assuming you don't currently have a business, and are looking for a loan to start one. If you already have a successful business, and are looking for a loan...then that's a different story. With an already established business, convincing them is fairly easy.