First and foremost, content is king. That's been true since the beginning of information. Having a super fancy blog with all the latest AJAX, jquery, Flash integrated functions will not make readers want to come back if there is no content. The largest key to having return visitors is to create new content that they enjoy and content that makes them want to come back for more.
With that said, here are a few points that will help your blog interact and be as reader friendly to your visitors as possible.
With almost all blogs out there, the name of the blog is on the top header. Make sure it is big enough to read. That is usually the first place eyes go to when opening up a new page. Adding a catchy phrase or line, describing the nature of your blog is helpful as well.
Your latest posts should go in your homepage. This is where all the new information is being posted and updated. Having a date and time is useful as it shows when the post occurred. It gives people a time of reference, and you should decide to post on a regular schedule, it allows people to know when to expect another post, or if they should expect a post anytime in the near future.
A comments link is the best way to interact with your readers. With comments activated, you can see for yourself exactly what your readers think, feel, and suggest about your blog. To increase interactivity, you can post questions on your postings that you want your readers to answer. This is usually helpful to them, because it gives them something direct to talk about, as well as making them feel like their voice is hear.
The right column is usually reserved for a collection of related info. This is helpful to your readers as it points them in other directions that they may want to go, after reading through your blog.
Following these tips, you're sure to be on your way to success!