Is it legal to open a business that sells knock-off items? If so, how do I become successful?

I have bought many designer handbags and accessories. I have seen websites where I can buy these items. But I don't know where to go to get information on if its legal. I would like to call my business, "KNOCKS OFFS" by Design.

You have not indicated what you intend to “knock-off” or whether you intend to make exact copies or similar items. In either event, selling “knock-offs” is always a precarious venture. And calling your company "Knock-Offs by Design" could be a magnet for real trouble.  If you plan to make exact copies and the items are covered by copyrights or patents, for example, you would be infringing on the rights of those intellectual property holders.  You could be sued, ordered to cease sales of those items, and required to pay to the IP holders what you have earned from your sale of the items, among other penalties.  If you plan to make inexact copies, what you are making and how closely it resembles the originals would determine your risk of being sued and losing. You must also be aware of the various federal and state unfair business practices laws. Building a business model based on someone else's designs is like playing Russian roulette:  you could get away with it, but just one bullet could destroy you and your business.  You would be wise to discuss your plans with an attorney fully versed in these matters before commencing operations. The answer to the second part of your question has been asked by everyone who has ever owned a business. When you find the answer, please let all of us know.  :-)