Step 9: Your first templates
Now for your main template I would suggest adding an editable region called content, saving it as a template and calling it at that, this is the template you can do whatever you want with.
Making some more focused templates makes sense - for example my blog template has a table in it, with a main column for content, there's an editable region there, an ad box on the right and below that links to all my recent posts, so each time I add a new one I only update my template.
I have a similar setup for projects.
For each type of template you'll need set it up before making your content pages, this will save you a lot of grief later on, you'll be able to say I need to update all my blog pages and do it with one template.