Optimising images for the web to aid your websites' search engine results is a fairly easy process once you have selected your keywords. Simply match your image names to the keywords of your page. For search engines to best recognize your keywords, separate them with an underscore or hyphen.
Eg. Main keyword for my page is - web course Melbourne
Other keywords are- web development course, building a business using the internet
My images, depending on how many I choose to place on my page will be named-
Either jpeg or gif images are suitable file extensions (should preferably be in lower case- .jpg or.gif) for the web- to better understand the difference between the two refer to the following Help Sheet.
If you have an option to add an 'alt tag' to your image- do so, it is simply a short sentence of text explaining what your image is, and is a chance to further use your selected keyword for the page.
Placing at least one image on a page will help to draw your visitor through the page as well adding visual interest, it will also assist in Google Image searches, used more and more in visual industries, and obviously on any website selling a product.
Try and keep your images to 100kb per image, this improves loading times, more about image sizing here.