I'm building an application using MC and I followed these steps:
- mapping your business process or your rules
- take technical decisions (i.e. decide if you want to centralize the private key or not, how to perform mining and so on)
- create a proof of concept. At the moment I'm developing using python and making rpc but there are a lot of possibile choices.
- create your network
- test and deploy
According to my experience, the first two points are the critical ones and take a lot of time if you have no former experience.