It’s always a good idea to think ahead before jumping into programming a large HTML5 and CSS3 site. Here are some questions you need to ask yourself when designing a larger website:
What's the point of the site? The site doesn't have to be serious, but it does have to have a theme. If you don't know what your site is about, neither do your users (and they'll leave in a hurry).
Who are you talking to? Websites are a form of communication, and you can't communicate well if you don't understand your audience. Who is the primary target audience for this site?
Which resources do you have available? Resources involve a lot more than money (but it helps). How much time do you have? Do you have access to a solid technical framework? Can you get help if you need it? Do you have all the copy and raw materials?
What are you trying to say? Believe it or not, this question often poses a huge problem. Somebody says, “I need a website.” When you ask what she wants on the site, she says, “Oh, lots of things.” When you try to pin down the answers, though, people often don't know what they want their website to say.
What are the visual design constraints? If you're building a page for a small business, it probably has some kind of visual identity (through brochures or signage, for example). The business owner often wants you to stick with the company's current branding, which may involve negotiating with graphic artists or advertisers the business has worked with.
Where will you put this thing? Does the client already have a domain name? Will moving the domain name cause a problem? Does content that's already on the web need to be moved? Do you already have hosting space and a DNS name in mind?