When it comes to deciding how you are going to take that idea you have and turn it into a profitable venture the first step to take is usually to do some research on potential clients/customers:
Who is your ideal client/customer?
What are their perceptions about your product/service you would like to provide?
What does it do for them from their point of view?
How can you increase the perceived value?
How much are they prepared to pay for it?
What is the best way to deliver it to them?
Which media is the best to use to attract them?
The surest way of getting the answers is to have a ready made product or prototype and to go cold calling on those that you think fit the profile of your ideal customer. You can also setup a website and then use pay per click advertising such as Google's Adwords or Facebook's Adverts to see what type of response their is to your idea.
look at your closest competitors to see how they are doing things, then you can work out how you can do it a little more different or better so you can differentiate your business from theirs.
A few ways you can do this would be to:
Use Google and search for them online, visit the results.
Browse their website if they have one.
Become their client/customer.
Collect their advertisements.
From these you can begin to ask yourself:
What exactly are they providing in terms of their value proposition how they are doing it?
How will it impact on your business venture and how can you respond?
What can you do better?
How can you do it better?
If you have any particular expertise on the subject of market research or have any experience with it that you would like to add please do... lets get the ideas flowing.