Again, if your blog has a large reader base, then businesses may be interested in paying you to review their services or products. Not only will you get a free trial using whatever these businesses are selling, but you will also get a fee for writing them a review and posting it to your site. Paid reviews (and other paid and sponsored content) can be big money, so advertise this service on your contact page to generate business.
To do that, you have to harbor a few fundamental guiding principles in your mind. Today, if you're at all serious about generating a full-time income (and more) from your online activities, then you need to focus on passive income as opposed to active income. Sure, the active income will help you survive. That's the scarcity mentality at play. But it's the passive income ideas that will help you thrive.
One of the cool things about Google AdSense is that it's so easy to get set up. If you have a blog or website, you can sign up for a free Google AdSense Account. From there, Google will give you a unique code that you will paste onto your website. Google takes it from there, tracking your page views, traffic, and earnings on your behalf. There is no upkeep or maintenance to get this thing going, which makes it a no-brainer if you have a website already.