There is no magic formula for making money in any way, online included. There is a formula, yes, but it’s quite mundane: sell people what they want to pay for. If you’re doing that, the blogging part is easy (well, okay, easier). If you’re not doing that, the blogging will be hard. Everything will be hard. If you love what you do, it hardly even feels like selling. I don’t “sell” at all, I just accept the money and do the work.
One way to sell people what they want to pay for is to strengthen your skills at something you really love and sell them. Blogging is a natural fit for me. If you have skills that are worth paying for, blogging is probably about the best activity you can do to boost your profile, get the work you love, and charge the rates you want.
Learning skills and reaching this point can take time. In my case, over a decade. I’ve been steadily building my skills and gaining experience. I have become a pretty decent jack-of-all-trades, master of some. 
As one person, I really can “do it all” for your blog. If you become an expert at something, your expertise is valuable to others. You can blog about and get hired for it. You can sell people what they want to pay for.
I think that in the next ten years, as computers and software replace more and more white-collar workers, freelance work will be the safest, most secure form of employment you can have.
Have you used any books to improve your writing skill and style? If so, I’d love to know which.
Freelancing is building its pace and the best of it is that we can accept and deny job or project requests as and when we want.
@ David – I’ve always been a writer and majored in English. I have run across so many resources and tutorials I couldn’t possibly offer a suggestion, other than perhaps Brian Clark’s Copyblogger.
@ Wayne – Many freelancers feel they must accept everything that comes their way, no matter how lame or onerous the work. It’s commonly said that beggars can’t be choosers. But the reverse is also true: choosers are not beggars. Be a chooser.