Blogging is something that requires patience, persistence and discipline. It may mean writing everyday for over a year before you really start to see any money from it. There are exceptions to the rule, but from my dealings with other bloggers, it seems to be pretty common to spend one or even two years building your blog, your brand and your authority, before making any serious amount of money.
The products and services you will be promoting to your audience must be relevant and good quality. Make sure you believe in them and know everything about them, because this will be crucial to you delivering the sales pitch to your audience. You need to build trust with your audience so make sure the products and services you choose to promote are trustworthy enough.