Frequent updating or updating on a regular schedule gives people reason to keep coming back.
Find your voice. It's hard to find something original to say, but no one will say a thing the way you will. Readers will appreciate your honesty.
While there's an audience for profanity and lewdness, you will limit your readership that way.
Spelling, punctuation, grammar. Learn them. Use them. Then proofread before hitting Save, Post, Send, whatever. While talking in internet-speak (u instead of you) is acceptable in certain cases, you will lose a lot of readers who will tire of trying to deciper your entries.
There are a lot of blogs out there. Give people a reason to come back. You can devote your blog to a theme or you can post a bit of everything, but keep in mind the message you're sending. Themes will attract people interested in that theme and turn away other potential readers. A blog that's too eclectic might turn off people who aren't interested in everything you write about. Think of the audience you're trying to reach.
Have fun and be yourself. Readers can tell when someone is enjoying the process or when they're blogging out of obligation. They might get bored by the latter and not bother to revisit.
Don't blog about things you think you should write about; blog about things you want to write about. Readers can see lack of sincerity often at a glance.
Use graphics/photos whenever possible to enhance and embellish your blog, but don't overdo.
Use links to related blog posts or websites. The blogosphere is about connectivity. Linking helps people follow conversations. So does tagging if your blog service allows it.
While long posts are fine once in a while and work fine on some themed blogs, they can get tedious to read on a computer monitor and you will likely do better with shorter posts. Being precise and concise can help cut down a wordy post. Also, break a long post into shorter paragraphs whenever possible. You might even be able to take the topic and make 2 or 3 entries out of it. Your readers will appreciate it.
It's fine to get personal, and in fact, a lot of readers enjoy the insight into people's lives and feelings. But unless you don't have anything to lose by revealing your identity (ie, job ramifications, marital strife), don't give away everything. Change some details, refer to people by names you make up for the blog or their initials, don't name your employer, and so on. Be careful.
Dressing Up Your Blog
You can find fun and interesting things for your blogs. A listing can be found on Blog Links.
Try to keep the layout clean and readable. Keep your audience in mind. Some folks handle bright or dark colors, a busy look, and/or small fonts better than others.
While frames are popular, they can be annoying.
Sound or music can enhance a blog, but it can also be annoying for people using listening to their own music on their computer when they visit your blog. It is especially annoying when it's music the visitor doesn't like. Better is a link on your blog to a music file.
Too many graphics or large graphic files take time to load and that will turn off a lot of readers. If your blog is on a traffic generator service like Blog Explosion, your blog might take more time to load than the 30 seconds the viewer is required to stay before clicking to the next blog. That means people won't be sampling your blog with that service.
Use a layout or colors that suit your topic or theme. Be sure the features and text are easy to find. Large headers can look cool, but require a lot of scrolling to get to the text and aren't advisable, especially for people surfing in via a traffic exchange like Blog Explosion.
Use the sidebar to offer interesting services. Many blogs offer quotes of the day, a daily comic, news, translations, blogrolls, links to interesting sites, what the blogger is reading or listening to, places to get quizzes to take, clocks, calendars, etc. Too many things, especially using Javascript, can slow down the blog's loading time and be too cluttered. On Cyber Chocolate, Shelly has a lot of things in the sidebar, but she's using the sidebar as a central location for these links, similar to the Blog Links page. She doesn't recommend including so many things for most blogs.
Promoting Your Blog
There are many ways to publicize your blog. Links to services mentioned in this section are listed on Blog Links.
Ping (notify) services like Ping-o-Matic that you've updated your blog. Some blogging services do some pinging automatically for you, though a few, like Blogger, require you to turn this option on.
Submit your blog to search engines to get them indexed. Don't leave things to chance.
Use titles for your entries. This makes it easier for your entries to come up in searches.
Use categories and tags if your blogging service allows them. Your readers will appreciate it.
Use a reasonable sized font and color scheme to make it easier for people to read. (See Dressing Up Your Blog above for layout tips.)
Submit your blogs to relevant blog rings, blog directories, and similar services. Be accurate in your descriptions. No one likes being enticed to a blog and finding something other than what they expected. Follow the rules of the rings and directories and keep your information up-to-date.
Visit other blogs that interest you, and leave comments with your blog's link. These will act like calling cards and the other bloggers will likely visit your blog in return. If they like it, they'll be back. They might even tell others by blogging about it, known as pimping.
Make sure you have an rss feed. That makes it easier for people to read your blogs, as many people read a lot of blogs and use aggregators to simplify the process. If possible, allow full syndication, not just titles or synopses. Nothing bugs me more than having to go from my aggregator to the blog page when I'm trying to catch up on 50 blogs at a time. It's a lot easier when everything is in one place and I'm more likely to read the entry that way.
Promote or pimp blogs you like. You might get a mention back. Also click on links you post to other blogs to make sure they work. This will also show up in their referrer logs if they have those stats on their blog and they might visit yours out of curiosity.
Give people a reason to read your blog. Write interesting things well or post easy to view photos or offer up fun and/or informative links.
Let people know you have a blog. Email friends and folks you know online and tell them all about it.
Join blog link exchanges and blog traffic exchanges.Actively participate in them.
Add your blog's URL to your email signature and if you frequent message boards, add it to your posting signature if allowed by the TOS.
Frequent updating or updating on a regular schedule gives people reason to keep coming back.