You'd laugh if you saw me messing with my blogger template. You'd see me squinting as I changed some little number and then previewing to see what effect the change had. I'm that techy. I do love messing around with my template, though, because every time I do I learn more. I really should make more backups.
Blogger users (like me) will learn a lot from this free (.pdf) eBook offered by Amanda Fazani at BloggerBusters.com (bookmark it!). It's called The Cheat's Guide to Customizing Blogger Templates.
Click here to download the templates, images, etc. that go with it (optional)
Also on BloggerBuster: 200 Quick Tips for Using Blogger Effectively