This is so easy but makes such a difference to the look of your blog.
Have you added things like blog awards, photo's, adverts to your blog sidebars and they stick over to the left? (or even the little tags that you have to add to be on stumble or blogcatalog or other seo type site)
I recently added a section for doing badge swaps with fellow bloggers at the bottom of my blog and this will help to keep that whole section looking great too. I have a tutorial for making a grabbable blog or shop badge here if you don't know how to add one to your own site for other people to grab. So far I just have the lovely Dollipops - I gave her my sparkly giveaway HQ badge which you can grab down at the bottom or I can swap for this badge which will go to my shop. Let me know if you are interested in a swap, just leave me a comment.
Centralise your Sidebars
Here's how to make them all neat and tidy and centralised, just like mine on the left are.
Open up the gadget/widget in your blog layout section or directly from your blog if you have the editing mode (little tools crossed over beside each gadget)
Before all of the html text write <center> and afterwards write </center> (american spelling)
That's it, click save and you're done, all neat and tidy :o) worked especially well with my project wonderful adverts which looked very silly stuck over to the left as they are so slim.
Happy blogging - see more tips and tutorials here.