When you try and get some money out of your blog, the first thing that comes to mind is advertisement. Especially if your blog gets lots of traffic, selling ad space sounds like a great idea.
Advertisement however comes with a design problem. To make advertising effective, the readers must notice it, yet it cannot be too distracting. If the advertisement is too distracting, it will annoy the readers and can send them off of the site.
Google Adsense is a very popular way to include advertisement on a blog. These ads are quite difficult to fit in a design. The image ads are often quite ugly and often jump from the website design horribly. The text ads also either look weird or they blend in way too well.
In addition the advertisement differs depending the geographical area of the person browsing the site and their language settings. It's strange to see a banner blasting the message in Finnish on a top of an English language site. Also if your blog utilizes the responsive design, where the layout is adjusted depending the screen size, these ads won't work with it at all.
Some bloggers host the ads themselves and even choose their advertisers. In order to be able to advertise on these blogs your business must fit certain qualifications. Also the ad design must follow the design rules of the blog and the ads can be quality checked before being published. This way the advertisement will work as intended and fit the overall look of the blog.
If you want to see an example of advertising that fits the design well, check Dearest Nature Blog. The design isn't responsive, but it's very attractive and approachable.
Photo by Karunakar Rayker under Creative Commons license.