If you’re new to blogging and interested in doing it for profit, here are a few things to keep in mind before committing yourself.

1. Blogging is easy. Blogging for profit is more difficult. I won’t go as far as to say it’s hard to draw a secondary income from blogging, but it’s definitely harder than most people think. It’s not just about producing content and slapping up some ads. Good writing, proper templating, ad placement, developing an audience… there are a lot of skills required to make a blog profitable, all of which you’ll need to learn.
2. Blog for the long haul or not at all. A huge majority of blogs fail in the first few months, falling into neglect and disuse. More to the point, few blogs see any profit during the first few months. Unless you can stick with it for at least a year, you’ll probably never see any return for your effort.
3. Pick a niche that you love and stick with it. General purpose or multi-topic blogs have difficulty developing a readership. Brainstorm the topics that you care about most, then pick one and blog about it exclusively.
4. Start with one blog. If you have a lot of items on your list of possible topics, don’t give in to the temptation to start a different blog for each one. By dividing your effort between several blogs, you increase the likelihood that all of them will fail. Put all of your effort into one blog to start. Once you get the hang of things, then you might consider branching out with additional blogs.
5. If you’re unsure, test drive. The fact is that many people don’t have the drive or stamina to blog for profit successfully. If you’re not sure, try a starter blog on a free service such as Blogger or WordPress.com. Feel it out for a few weeks. If, by the end of this time, you’ve stuck with it and feel like blogging is right for you, go ahead and commit to the effort.
6. Place ads wisely. Some people recommend not placing ads on a blog until it has matured somewhat. Others recommend putting them up right away. There are advantages and disadvantages to both approaches. Just be sure to place your ads tactfully so as not to overwhelm your readers. Put the user experience in the first place.
7. Enjoy yourself. This is the real key to successful blogging. If you pick a topic that you love and blog about it with passion for months and years on end, your blog will build a readership, generate income, and generally be a success. If, however, your blog becomes a chore to maintain, it will inevitably fail.

The main point I want to convey is that many people try to blog for profit and fail. If you approach the task with the right expectations and some proper planning, you will succeed.