Here are some models to help you get started. These two models are great frameworks to think about your business ideas. You're going to constantly change these models, because nothing really stays constant and if there is one constant, it's change.
Models are great because they're shortcuts. Helps you think and process information faster.
Lean Canvas: The easiest business model you have ever used!
You can find more information here: http://www.businessmodelgeneration.com/canvas
Porter's Five Forces: Old school model that most business school people will point you to.
May the force be with you: http://en.wikipedia.org/wiki/Porter_five_forces_analysis