I use relevant images in my blog post. An informative article with perfect image helps in visitor engagement. Good images attracts the attention of visitors and improves the readership and controls the bounce rate of your website.
I use relevant images on my site to help improve the look and also to pass on a message I don't think images on your website bring in more traffic . But a cool new social media site which you can use to generate traffic from images is pintrest you should give it a try.
Yes, Pinterest is something to utilize. Images do increase traffic but they have to be tagged properly. Don't just use photo1 or photo2. If you have a picture of someone using the product you're promoting you want that picture's description, name, and tag to have the action and name of the product posted.
Dont know what you mean by cartoons. For a serious topic of website, you probably cannot try using cartoons. Using good, informative or funny images can help especially on Facebook, Google+ or Pinterest.
You can't use cartoon character on your blog or website just only for getting more traffic. You can use any relevant images, which look simply professional.