Do a SWOT analysis to see what makes more sense to you. Which one fits your strengths and avoids your weaknesses? Which has the most interesting opportunities and the least ominous threats?
Then do a business plan. Figure it out according to your specific case, looking at what suits you, what matches your strengths and weaknesses, what you want out of the business, what resources you have, and many other questions.
That's why people plan before they start. Every plan is different, just like every person, and every business. Find your own best way.
Question added to topic Starting a Business • August 21, 2007
Should I open an online store or a real, physical boutique?
Should I design my own shoes and sell them on a website or create a boutique that will house the type of shoe I want to make?