...for want of a better place to put and organize them.
Once you've analyzed the structure of your pages, it's time to take a look under the proverbial hood and analyze your existing markup for presentational HTML that can be replaced with structural markup.
At the begining, give each div a border. For example,
div {border: 1px dotted gray; padding: .5em}
This will help you see where they begin and end, and also
whether or not you have any nesting going on.
Write your CSS for element selectors first (<html>, <body>, <p>, <h1>, <h2>, <ul>, <li>, etc.)
Use contextual or descendant selectors as much as possible. This will keep your
markup much cleaner. For example,
#subnav li {border: 1px solid black; padding: .5em; display:
inline}
will only affect list items that occur within your
subnav div.
Here are some links to great sites with CSS suggestions.