This is a primary question for speakers just getting themselves started in the business. It feels like an 800 lb gorilla. We go through so much preparation work to make sure we're a good speaker, that we have a great message, and that our website looks just so - and then we're left with nowhere to speak.
You can spend a fortune on one-sheets, brochures, and a demo video of you in front of an audience, assuming you can get one together - then spend another fortune getting in front of people you think will pay you to speak. If you've got two fortunes to spend, you might consider this option, but its still far from guaranteed.
The easiest step most people miss is free, and can be amazingly effective. Speak about the fact that you speak. Tell your friends. Tell your boss. Tell your church. Tell your Toastmasters club, your chamber of commerce contacts, and even your drinking buddies. Go to networking groups, and tell them. Tell your Facebook friends, your Twitter tweeps, and your Linked In contacts.
If people don't know you speak, if they haven't heard you even speak about the fact that you speak, you may as well be sitting in your house knitting - you'll get the same number of speaking opportunities.
Once people know you can speak, you'll be amazed how quickly they will get you in touch with the people they know, and the people the people they know know, etc. Especially if you take the NEXT step. It's a concept that may be tough to swallow: after you speak - you ASK them to help you find places to speak!!
After a few initial opportunities - you'll have a good gauge of how well you are able to Speak & Deliver in front of a real live audience - by how many people you didn't know before start referring you to their friends.
ASK. SPEAK. DELIVER....and repeat.