When I first decided I was going to setup LM-BLOG I asked myself one question over and over. That question was “what topic?”
At first I chose money and fuel usage as my topics for my blog. However during a period of 3 or so months when I did no work whatsoever to this blog I realised that I could really run the blog with a much wider topic. At that point I chose technology.
The blog still attempts to keep the same topic but has no grown into a much wider area where I show mostly “help” topics, by this I mean advising on things to use and also offering thoughts are reason for why to do things.
For your blog I will say that you should always decide on a topic, when you first start out telling your users what your topic is and will be may keep them interested or get them to tell someone who will be interested.
Choosing a topic will also allow you to much better advertise on a website just like your own. For instance picking to advertise via Entrecard on a site in the same category as your blog.
However what I feel is the most important reason for having a topic for your blog is so that you can have a way to go. It gives you a direction for you to aim all your posts.
It can also make you need to change blog topics if you discover while working on content that you actually dont or cant make any. I will quite happily admit that my first topic of blogging (a more personal blog) was really hard to work on and was really the reason that I formed LM-BLOG.
What Am I Saying ?
I am saying that you should think of a topic that will interest you and that you will be happy to write about.
However also that once you have thought of the topic think of content for it to see if there is enough.
Good luck with choosing a topic and with your content.