Use 'Request Policy'
I recommend the use of the Request Policy plug-in for Firefox. It blocks all requests to third party websites and indicates that it is doing so. Then, you can temporarily or permanently lift the block for all requests to that site or only requests from the site you're using at that time. (It's easier to understand if you just use it and play with it.)
On many sites I use, there are an amazing number of third party sites that are blocked by Request Policy without my use of the originating site being affected at all. If an image is blocked, it shows the image box as greyed out with a little red flag in the middle that can be clicked to indicate the name of the site being blocked.
The first time you use it, there is the minor frustration of having to go through the list it presents and deciding which ones to allow, since many sites use third party sites to deliver required content. However, I feel it's worth it to avoid the shedload of crap and all the inevitable tracking stuff that will be there.