A site that is not planned is usually terrible to use. A site that is well thought out is likely to maximise repeat site usage through attractive features and minimise the loss of visitors due to impatience.
Who is the page for? What will they find attractive and useful? How much time do you have to build the site and maintain it, how often? Is it a core part of your business?
What do you want to achieve from the site; provide information, gather information, sell, interact with others, blog or show off your holiday picturess? Is it essentially a brochure?
People won't look at most of the site unless there is useful content on it. You have to set aside resources (most importantly time) for site development, promotion and site maintenance.
So, plan. Get a sheet of paper and draw a tree diagram of the site you want. Each page leads to another page or pages. If you want a database driven site, the same applies, although the planning is often more complex.
From your initial page have your branch pages coming off it. And if the site is big enough, other branch pages coming off them. Not sure what this means? See the google site for a simple set of navigation.
Now you have a fairly messy tree diagram in front of you - is there a better way of doing it? Can you simplify the navigation? Have a look at some similar sites to the one you are going to build. What makes the best sites good is ease of use and having somewhere to go.
What should the site be called? Many sitenames (where you choose one such as sitename.com it is called a domain name) are taken.
There are alternatives to domain names (domain names give the siteowner the most control over a name), as most internet access includes some free space and there are some free services that exist (such as free services for blogs and free web space that often includes advertising).
These latter options tend to give the site owner less control over a site name. It may not be appropriate to have your own name as the site name (be very careful about putting your personal phone number(s) and address on any website as once it is released it is hard to take back). So you might want to have some sort of anonymous name, but note that it is hard to remain anonymous with whois tools for mining information such as that from domain tools and dns stuff.
Six tips on choosing a domain name, some of these tips also apply to any site name:
There are a number of domain name buying guides which I won't replicate here - see for example, the Domain names buying guide from PC World Australia and the ICANN FAQ. You may wish to checkout namecheap or godaddy (both US based).