Learn on the little guys
Small businesses don't have the budget for experienced designers. Some will try to get their nephew's dog to do it for free, but others will realize the need for someone more skilled than that. That's where you come in ;-)
You'll have to work cheap, but that's better than working for nothing while you experiment in your basement, right? Build some confidence and experience and start looking for better gigs. You should also look for professional critique wherever you can find it — don't just rely on the praise of under-paying business owners.
Some great places to start are locally owned restaurants, clothing shops, small manufacturers, fashion companies, etc. You'll also find lots of low-paid freelance jobs around the web. The thing I like about local businesses is the face-time — you're forced to learn how to present.
Study while you have time
While you're working yourself to the bone and living off pizza, do some reading too. You need to learn the basics of design and conceptual problem solving. There are plenty of questions around here addressing good resources, so dig around while you're waiting to find your first big project.