The way you approach this sort of task really depends on what you are trying to achieve with ExpressionEngine.
As a content management system my assumption is that you wish to provide a means for you client to have editorial control over some, or all, of their website. It is this question which is crucial in determining how exactly you will structure your website in ExpressionEngine.
One of the beauties of ExpressionEngine, over other CMS/Blog platforms, is the ability to build your site (templates) using entirely your own code, and then as and when required utilise EE tags to pull in dynamic elements from EE. Thus, it is entirely possible to completely recreate a static website inside EE by simply creating templates corresponding to your static pages and simply pasting your own code into them. This then allows you to systematically replace any areas designed to be dynamic with EE tags as and where appropriate.
Templates are analogous to the static aspects of your website. These are the areas you won’t typically allow clients to control. The elements on the page you wish to provide editorial control over need to be dealt with differently - using Channels and/or Pages, depending on the nature of the content.
For something like a Blog, this is very easy. Create a new Channel called Blog. In the template designed to serve this dynamic content insert the appropriate EE tags to call in the channel content. In fact, in earlier EE incarnations a Channel was called a Weblog, due to it essentially being exactly that. It’s name was changed to reflect the fact it could be used for so much more than this.
If however you have more demanding needs, for example your client needs to control ALL elements of content, even those seemingly static ones, you have to get more creative and look at using a Channel of static content snippets and/or Pages module. You can even go a stage further and use something like Structure which allows you to use Posts as Pages.