It is quite reasonable to expect there to be some form of advertising on blogs.
After all, the bloggers are paying for domain names, hosting and possibly other bills to provide a service for free.
So if there is a chance of a small income, why not? However, filling a blog full of advertising can look dreadful and gives the impression that it is the value of your readers that matter to the blogger, not the readers themselves.
There is a fine balance between sufficient and too much.
If you read Google's AdSense guide they recommend displaying three AdSense units per page as the optimal way to earn money from them.
And with their range of small to huge advert banners, you can certainly fill your site with advertising.
But, where do you place the adverts for best effect? In the content, in the navigation, above and below the post or one or more of a lot more options open to you? As a rule, ignore Google's insistence that 3 advert blocks (plus their search and other advertising units) makes the most money.
Yes, it gives plenty of chance to build revenue, but even three blocks is too much.
Instead, just two advert blocks around the page.
This does not always need to translate to two Google blocks (or two affiliate links).
It just means keep to two advertising positions on the page that look subtle, but are visible to visitors.
You can put a couple of similar sized Google blocks and affiliate links together to form an advertising block if you want to, just make sure that they look good together and look as though they are meant to go together.
So, where to put them? Well you have to balance places on the website that people will look with not being too 'in your face'.
Add some advertising to your main navigation in a similar style to your navigation and it will blend in well.
Maybe put a wide block across the top of the screen, or a second block further down the navigation, whichever works best for your blog.
Some people worry that this means that there is no advertising at the end of the post, but this is what you want.
Those people most likely to click on adverts are those that have just arrived.
Therefore, put the adverts where they can be seen when the page is opened.
However, those that have read your post in full and reached the bottom of the post are liable to be able to be encouraged into becoming regular readers, so give them more to read, not adverts.