Basically you need to present an idea for a form of technology that someone already has. A start-up can simply take an existing system and find a new way to run it that is more efficient or effective. Start-ups don't have to create something radically new, but they do need to present something useful. If your idea makes life with technology much easier you have a great start-up idea. A good way to figure out if your idea is a good one is to try it on people who use technology frequently. Run some surveys to get an idea for the sorts of things that would make life easier for them.
If a start-up is disconnected from what is going on in the technology industry it will fail. You need to know what other companies and start-ups are doing in order to prevent being redundant. A start-up could fill a niche created by another brand new technology. The people you select need to be folks who know everything going on in the technology industry.
One of the other things that you will need to develop a start-up is a good team of people behind you. Pick people who are friendly and who provide good energy and support. Launching a successful start-up is a very difficult business and it requires the time and energy of a group of people. You need to select qualified people who have as much of an investment in the start-up as you do. You don't want to just find another employee-you need to find someone who has a passion and interest in what you do.
Another very important part of launching a successful start-up is raising enough money. It takes a good deal of cash to develop a new product or service and especially in the technology industry. You a great idea mostly because you need to sell it to investors. Be cautious not to spend the money too quickly. Develop your product and keep a store of cash for unexpected emergencies.

Try to create a complete package when you sell your idea to investors. You want something cutting edge and well designed. Half of the business of a startup is selling a good idea; the product's effectiveness will largely depend on the way people use it. Your job is primarily to find a way to sell the idea.

Developing and launching a new startup is an extremely difficult thing to do. Your hours will be extremely long and the challenges will be great. You will face setback and problems with your staff. If you have planned well, selected the right people, and raised ample funds you should succeed. However, the really important part of the job is coming up with a great idea. Make sure you protect your idea well; in an age of quick changes in technology your idea could be taken and turned into someone else's good idea overnight.