I've been creating more and more systems recently and I find more and more planning and preparation I do before starting the project.

I determine what libraries or frameworks I will be using, what languages, the basic architecture of how the site will flow, etc.

I've also heard of other design processes such as hanging styrofoam balls to show where classes are and how they relate, which is a process I've never heard of nor do I know how it works.

Is there any software that helps with this process? Are there any guidelines or steps or do you have a recommended set of steps or guidelines that you follow when designing a new project?