I've been out for a while - moving house and moving internet provider. It has proven longer than I expected, but I'm finally back and on the scene!
I would like to say a few words about readership and money. The first thing to note is that, if you think that you can just jump into blogging and make lots of money, you're in for a sore disappointment. In fact, building a blog and putting ads on it right away is a sure way not to succeed, because a lot of directories and indexing sites will look down upon blogs with few posts but a lot of ads. As everything (legitimate) in life, money requires investment - in this case, of time, effort and creativity. To make money, you have to earn loyal readership.
In other words,
Blog Money = Loyal Readership + Number of visitors
1. Loyal Readership
I would define readership as people that a) visit your blog b) stay long enough to read your posts and c) are willing to interact with your blog (by posting comments, clicking on links, buying the merchandise you suggest etc). On top of this, loyal readership means people that keep on coming to your site, keeping your visit numbers up consistently. To achieve loyal readership, your blog must be meaningful to a number of people. This in practice implies that you must have a brand, a certain personality that involves the topic, writing style and presentation.
Branding is of course a huge topic of marketing, and I will not dwell on it for the purpose of the article. Suffice it to say that you have to satisfy two customers: the audience AND yourself. If you go only by what you think the audience wants, your creativity will be affected. If you go only by what you want, there will be no readership. Branding also requires building a pleasant place - a website that visitors can find a temporary 'home' in. Of course, a number of your visitors will come from RSS feeds, but the bulk will still be people that physically access your site. Therefore, make your blog a place you like coming to - not too cluttered, not too many ads, not too slow to load. On this I will come back another time.
2. Number of Visitors
On the other level there is the concern for the number of visitors that come in. This is linked with the topic you are involved in, how popular it is, whether the topic is on an upward or downward trend, as well as your ability to 'reach' for that audience. Some good ways to find what subjects are popular is on bookmarking networks as delicious or magnolia, 'news' sites like digg, or on article databases. Again, this is a large topic that is worth more in-depth analysis.
The combination of readership and visitor numbers is related to establishing one's niche in the market: creating the place that is only yours. Setting up a niche requires intuition - the niche must be big enough to have sufficient readers, but small enough to muster a loyal readership. Obviously, the choice of the niche has a great impact on your ability to gather money, because only where the stars meet - there is loyal readership AND a high enough number of visitors - you will make a lot of money. Yet there is no guarantee that going for a highly rated topic would allow you to win a lot of money: logically, if the topic is highly rated, a lot of bloggers already jumped on that bandwagon and 'filled' the niche. Of course, there is still room to leave your mark, but you have to put a lot of effort to 'get your foot in the door'. Another solution is going for a less rated topic, which may not already be as crowded. The less rated the topic is, the higher the chances of building a loyalty, a key ingredient in the mix. In any case, however, there will be a lot of work involved in establishing your blog as a 'voice' for the topic you choose.