The key to a user-friendly website is a simple and easy-to-go-through navigation system. Over a few span of time, I have been involved in building some very extensive and complex websites. Such large quantity of content and pages make it very difficult to make a website simple and agile. As lots of navigational pages are added, it becomes very difficult to keep the whole navigation responsive.
While you are working on a highly-complex website, the key to your success is to keep your client in loop and keep asking for his feedback during the design process.
After the design process is completed, before going to the technical phase, you need to understand fully what the project is about. To do so, the first thing you need to do is to conduct a research on your target audience. Only after the audience is determined should you move ahead with information architecture and wireframing. For instance, the website you have to make is about entertainment. You will have to do research on what type of content users look for on entertainment websites and based on your research, you will have to make sure that the content is placed accordingly.
After the audience research comes the most important task i.e. to discuss the website with your client. To better understand which sections of the website are most important and which sections are interrelated to each other is critical to make it user-friendly and easy-to-navigate.
The easiest way to manage a large quantity of content is to contain them into few relevant categories in the navigational bar. You might find some pages not related to the main categories so you will have to make supporting menus to accommodate these pages.
Integrate this streamlined content into your wireframes and conduct a users test. See if a common user can easily navigate through the website and find his desired page effortlessly.
Moving to interface design, you should create mockups for mobile version of the website. Make your clients understand that the mobile website has the same look as the web and there is no need to make a new skin.
Getting involved in the design phase is very important to come up with full-responsive website and to understand this, you must think like a user; how he thinks, reacts and surf. Making a responsive website is not difficult at all.