While you're still working a full-time job, here is a list of things you can do on the side to explore an idea for a great new business:
1. Research your idea. Figure out the market, talk to prospective customers about what they would like, see who your competitors are, and so forth.
2. Undertake legal incorporation and trademark protection.
3. Claim a web URL, build a website (or have it built) and get company email accounts.
4. Get a bank account and credit card (most likely you'll have to use personal credit at first).
5. If appropriate, initiate a Facebook page, a blog and a Twitter account.
6. Develop branding.
7. Talk it up to your network. Try to find interested parties as co-founders, staff, investors and advisers.
8. If necessary, build financial projections and draft a business plan.
9. Engage in personal financial planning, including cutting back on expenses and budgeting for startup costs.
10. Create a mock prototype and presentation for potential investors or customers.