At the same time quality, placing and styling of the images is important too. As I have already posted different articles regarding images in posts, like where you can find copyright free images, how to resize, change format or improve the quality of images, animated GIF image creator, free image hosting websites etc. So here's one more in that list.
RoundPic.com: By using this tool/website, you can upload and convert a simple unmodified image in to a round/smooth edged picture. The work done by the tool is quite simple, as it just cuts the edges (dimensions are as per your requirements). Although you can do this with any image editing software, but that will be very time taking and quite boring too :)
So simply visit this website whenever required and complete your work within minutes. Embed the images in to your blog/website, as these modified round edged images look very professional compared to normal images.