There are lot of different tools, alternatives you could use, here are preferred ones by me: MiddleMan as a static site generator, I also use Foundation by def

There are lot of different tools, alternatives you could use, here are preferred ones by me: MiddleMan as a static site generator, I also use Foundation by default or can use Bootstrap if someone prefers it. Slim templating engine as it is very easy to read. ConceptBoard or InvisionApp are good for iterating over feedback. Trello or any other of similar tools can help you allow visibility what is happening. It is very important to do things at the right time. First develop wire that would capture requirements, original idea. Then design interface based on wires, and model data (very important step). This is when you can start writing tests, not before. Then coding rest of the interface. BTW, this also works for developing API and works really well.