Keep in mind that I am no expert. I'm still new to this. But I have learned a lot and willing to share the results of my tiny experience with you.
Yes themes are the biggest thing. You can write the best about page in the history of history. But for the most part people do not care. If they look at your blog and see that you're talking about World of Warcraft they'll assume it's a gaming blog. Despite the other topics you have already blogged about.
For instance take a glance at my project (a WIP really) but you'll see that may be clumsy, not entirely streamlined. But you get the idea of what's it about by looking at it. I'll be getting some reviews done here shortly and I'll even post their information here if you'd like. Maybe what can help me will help you too.
Another thing. Content. Stock pile it like a squirrel getting ready for winter. If you think you have enough get more. Have a lot of content on your initial launch and then have some more that you can release a few times a week over several weeks. This keeps your blog current, and promotes more visitors and retains visitors. If they're is always something new and up to date. You'll keep people coming to you.
DO NOT OFFER COMMENTS if you're starting off. Zero comments= a dead site. Like my site listed above. No comments= death. No one is willing to say anything. If you have a lot of people chatting about something then that encourages others to come and chat and etc. You'll know when you're ready when you get a lot of messages asking for such a feature.
Oh and don't forget about your SEO and the rules involved with it. Master the SEO and you'll be good to go. Use some keywords and create SEO rich content. The higher the SEO rating the more people will come to you ...so they say.
About your contact page (if you're going to use one) have like an email@example.com or firstname.lastname@example.org along with your contact form. A reviewer of my site stated, quite emphatically, that she hated how people didn't have a contact email typed out. She wasn't sure if they forms ever worked, or if the message ever gets sent. So having the address simply typed out (no links) made her feel comfortable with the fact that her message was sent.
Another don't have people scroll too much. I've reduced the length of my home page because I found that people will only move the scroll wheel twice. Which put them at half of my home page. And they missed everything else. So short and simple.
Create a newsletter. I've read something like that helps keep people engaged over time, or you can people sign up for email notifications.
Again I'm going to get more reviews and analysis surveys done on my site and I'll be more than happy to share those reports with you.