Try to look for subjects or topics that pay more from per click among others. Check out adwords and adsense to know how much each clicks on a subject costs.
Heading to a good start
Now you have created a blog, you should start advertising you blog. Submit it to various search engines, refer it to your friends, post your blog address at every appropriate place you find on the net, any place where it will get noticed like classifieds, discussion forums etc.
Different ways you can earn money from your blog
One of the best ways of making money of your blog is google adsense. Create a google adsense account and register your blog with it. Google adsense then allows you to place ads on your blog. They will place any ad that has keywords related to your blog. Once a user happens to open your blog and click on the advertisement, you will earn money on it.

There is also the blogads service that offers certain amount of flexibility over the type of ads appearing on your blog. This service is not based on a pay-per-click system, meaning it will earn you money based on the number of times your blog is being viewed and not on the number of times the ads have been clicked. This is because they pay for the space of their ads on your blog for a certain period. Their sign up options are free and after joining, you can determine the type of ads to be put up on your blog as well as the advertising charges. Once your offering is announced to companies, consequently, they will contact you for an ad space on your blog.

Another ways to make a earning from your blogging activities is to become an affiliate partner to another company. There are a lots of popular affiliate program available over the internet which provides commission to its partners for every click on the ad placed on their blog. You will also get a percentage from the sale of their product made with the help of your blog. There are plenty of affiliate programs available on the internet with varied commission percentages to choose from. Some affiliate programs even offer profit sharing.
If you are blogging for a specific cause, you can still take advantage of it in a positive way. You can earn money blogging for a genuine cause. You can ask people to give donations for a specific cause, though most of it will go to you. To assist you in getting payment you can use the PayPal donation button and put on your site.
You can also earn money while blogging about unique merchandise and then offering them up for sale simultaneously in your blog. There are people who would gladly spend for merchandise that are custom-made, unique and totally out of this world. Edit your blog headline into a catchy one, create your very own logo and then offer up these kinds of items with your logo in it. It will be a sort of brand tag.

The gist
Do not just concentrate on any one of these way of money-earning opportunity. Combine these methods properly and wisely and earn more.

In the end
As the blogosphere develops, evolves and takes with it lots of internet users, so as earning opportunities increase by blogging. Just think, you will enjoy blogging as a hobby and earn in the outset too! Isn't it great?