Once you've a business idea, how would you test it?

I guess a safe answer would be to do survey regarding your idea in the market you want to introduce it. By my personal experience, I believe innovation plays a vital role in deciding the future of your idea. You also have to keep in account that just because you have a good product doesnt guarantee its good sale response. Organising brain-storm sessions on your ideas, listing the pros and cons of it from the individuals involded in the thinking process may lead to some insights about the success or failure of the business idea. :)

Write a business plan see how much it needs. Its hard that I know but make sure you do the savings for the enough fund or capital you want for your business,you can also get a little help from your family or even friends too, but first of all from yourself too just start small then as time goes by everything will be just fine. Believe in yourself.