I'm on a roll now with Blogger... I think!
First of all, you need to know that you can add as many blogs to your account as you wish, and delete them with a quick push of the button as well. You can even set them so no one can see them but you. You just need to come up with a unique enough name that's still available, and even that doesn't seem to be difficult.
Here's a site that has an excellent tutorial on customizing templates, and what the template code means. Don't be put off by all the ads on each page. It's very clear and thoughtful writing, and in addition the templates are very customizable and free. It has links to tutorials on more css stuff, like adding images behind text or on top. His writing isn't arrogant, which is unusual for code specialists.
If you grab a template and attempt to upload it to your test site, and get an error message, I learned a work around that solved my problem. (Although you folks on Mac, can't help you if it doesn't work.) I use Firefox. If you clear the cache (Tools> Clear Private Data> Cache) then try to upload again, it will probably work. If that fails, use Internet Explorer to upload.
The template code is much simpler than it appears at first, once you see the breakdown. It's just a bunch of css really, and is easy to switch out values. But in the tutorial he makes it clear where to be careful in switching things. (On sizing of the whole blog.)
Anyway, I have my sample blog set- waiting to hear from S. before posting it- but it looks quite nice with three columns so not the usual wasted space.
Blogu has many nice add-ons and info too, but what I'm referring you to above goes to the heart of Blogger design.