Whether these images are pictures that you've taken or graphical images, you will gain more attention to your post/page when you have visual images to break up the straight text.
BUT, make sure when adding images and icons to your site that they are royalty free. This means that you can't just go to Google, find a picture and post it on your site, its not your picture! Although, some sites allow for reprinting/reposting of images on other sites, to stay on the safe side you should use images that are made for the purpose of republishing.
Icon Archive – I love this site, all the graphical images I put in my blog posts are from here. A huge library of free icons.
Find Icons – Another great site to find free icons. Also gives upsell option of great paid icons.
IStockPhoto – Great site to provide high quality royalty free stock photos. Monthly Subscription payment as well as pay-as-you-go program.
Dreamstime – Royalty free photos on a pay per download option of a monthly subscription option.
There are many more sites out there for royalty free photo options, but the ones listed above are the ones that we currently use and some we've been using for several years.
Remember, the use of images, pictures, icons and videos are a great bonus when creating website and/or blog posts to grab your readers attention.