Most Joomla! developers make the mistake of creating too many unnecessary sections for their sites.

Most basic website only truly need one section (call it "articles"). Make a category for each different area the site will need. This will keep your Joomla structure clean and simple for you or your client. You can always add more sections later! The only way you'll really need a ton of sections is if each different area of your site will be broken up into smaller areas as in a magazine site.

Be conscious of your category names, as most SEF plugins will include the category name in the url (see "basic-joomla-tutorials" in the url of this page?).