Launch a business after 50 - 7 tips to help you start the right company, without risking your financial security.

A friend sent me your September 6 column on the 50 Best Companies for People Over 50, which is interesting, but at age 58 - after 36 years on the big-company treadmill - I'm getting ready to retire, and I'd much rather start my own business than go to work for someone else. The trouble is, I don't know what kind of company to start. My corporate background is in marketing, but my real passions are gardening and landscaping, and I do have decades of (successful but unpaid) experience at that. Would it be crazy to start a landscaping business? Any suggestions on how to decide? -Garden Guru