The first thing you must do is determine if your good idea can translate into a good business. Who are the customers? How many of them are there? Are they willing to pay, and if so how much? How much does it cost to deliver the product or service? How much does it cost to market the product/service?

This can be done with a simple P&L, the first person you need to convince that this is a good business opportunity is yourself. That is usually not hard since it's your idea and you obviously think its a good one, but be critical of yourself. And once you have a basic plan ask some trusted people what they think, see if you can convince them that it is a good business potential.

After you have done this you can move on to other things like finding technical people and creating a business plan. A lot of the heavy lifting for the business plan will already be done based on what you did above.