It's not always easy thinking up something to write about. However frequently (or otherwise) you update your site, you have to think of a topic, decide whether your users will find it interesting, estimate whether it will bring in ad clicks and turn it into content.
Often, that's not a problem. You might be bursting with things you want to say. Sometimes though, you'll be left scratching your head and wondering what on earth you can blog about.
One solution is to build a long-term plan.
Start a project that you'll enjoy doing, that will take a long time to complete -- and that you can write about at each stage.
So if you had a website about photography, for example, you could set out to take a picture of every church in your county. Each time you drove out to a church, you could write about the drive and say something about the community there.
Users would know what to expect, you'd have one post idea decided on a regular basis, and you could have fun doing it too.
That's one important criterion that any project idea has to meet. If you think you'll get bored in the middle or won't be able to complete it, it's probably best to choose something else. Users will admire you more if you actually complete what you set out to do. Trust me. I've been there, done that.
But you also have to consider what sort of ads writing about the project will bring in. There's no point in putting a huge effort into a topic that will only generate pennies in ad clicks. Before you commit yourself then, write one post that describes what you're thinking of doing. Take a look at the sort of ads those keywords bring in and track your clickthrough rate.
If you earn well off one post like that, you'll have a long line of high-earning posts coming up.
It's Del.icio.us!
Furl It!
