In my experience, if you're asking the question you're "ready enough."
With everyone's first company, you don't know anything and you're going in blind. You figure it out as you go. You read blogs and books to help avoid the "obvious" pitfalls, but even so you end up making half of those mistakes yourself.
So go ahead, and good luck, and don't forget to come back here when you have more questions!
My advice: be optimistic yet careful. Why don't you start by doing a SWOT (strengths, weaknesses, opportunities, threats) analysis on yourself?
Also, I really liked this comment in a book I reviewed recently:
"Before you even consider opening your own business, it's very important that you understand the value of knowing how to make a sale. If you cannot sell, do not go into business." (Bill Dieruf, The Successful Management of Independent Business, page 63)
Other tips? Take a close look at your finances (do you have enough capital? What would you do if you had to go several months or even a year without an income?) and start to develop a business plan, even if it is somewhat informal. The dean of McMaster's business school, said a few years back that until you can visualize every aspect of your business - not just the cool or fun parts - then you are not really ready to get started.
There is a lot of information available online to help you, sites like ours (CanadaOne.com), Fast Company, Inc. and others. Also, you might enjoy an article I wrote a few years ago: Should I Start My Own Company?
You know you can and are ready as soon as you start spending some meaningful time thinking and executing your idea/business. As soon as you start going to bed at 3AM in the morning after working in your "little" project. If you are not willing to do that, or are not doing it already, then starting a business is probably not for you.
When someone asks me that question I turn it around and ask them, "Why do you want to start a business?". There has to be a driving force from inside of you that wants to make a marked change in the life you are leading.
There appear to be two things that you need to ask oneself:
I wrote a popular post on doing what you love that may of some interest in the context to this conversation.
Keep your full time job and start something on the site and see if you like it. For me, I started doing contract on the side 10 years ago. At first it was one job every 2-3 months over time the jobs got bigger and closer together. About 3 years ago I went to do a four day work week (32 hours of work) about 2 years ago I went contract full time. Now I am looking at switching from contract to products.
My lesson is that things did not happen overnight, but if you keep it at things will work out.
From personal experience is that being self employed