One question that often comes up when discussing making money online by blogging is how many blogs you need to make money blogging. This is really hard to answer so I will answer it with my own experience. Everybody has different approaches so what works for me might not work for someone else, but I have years experience doing this so I will go by what works for me.
As I have said before, you can use Hubpages and Squidoo to make individual articles that really are not blogs. A blog is centered around a theme and you post to it at least 3 to 4 times per week in order to have a chance to get it found by the search engines. By getting found by the search engines, it has a much better chance of getting decent traffic. I am not going to use Squidoo and Hubpages in my figures for how many blogs you can use effectively because you can write a single article there and then pretty much forget about it or just update it occasionally. A blog has to have your attention in order for it to succeed.
I have found that when you are just starting out, you really should focus on the one blog you have. Try to write every day for at least a month. Once you get 30 posts on the blog, then you might think about creating another blog. Two blogs give you more chances for more traffic which results in more money. Remember, you now have two blogs and you still need to write daily. It may be more difficult to stay up with at least one post per day on the first blog, but you should write at least 3 to 4 times per week.
After you have gone another month, you can start another. By now, it is possible that you are getting some traffic and generating some revenue. I have a number of blogs. Sometimes, I start a blog to see where it might go. It might be easy to post to and it might work. Often, it does not. If it does not work out, there is no need to delete it. I leave it and move on. That is why you see the high number of blogs on my profile.
I have settled in on 3 blogs that get the most of my attention along with the individual posts I make on Squidoo and Hibpages. Three blogs can get plenty of attention from me but when I get to a 4th and it starts taking a lot of my attention, one of the other 3 usually suffers. Yes, you can make a dozen blogs and probably keep up, but I am saying that 3 is my optimal number.
Let me know what works for you.