Image searches like google image search have huge potential to drive search engine traffic to your sites and therefore increasing your sites traffic. There are certain aspects that defines images, by optimizing these aspects you can drive a huge flow of organic traffic to your site thus increasing your sites google search rankings.
So here we starts,
To reduce your sites page load time you should keep your images size as small as possible offcourse without sacrificing image quality.
Using a large image and reducing it's size by applying height and width tags will not going to help you but they will create trouble for you. If you use a large image and apply height and width tags to reduce its size actually it loads full size and then browser will resize it according to height and width attributes. That means here not only extra loading time but also a resizing time will be required which will cause your webpage loads slowly.
Keywords in File name
File name will surely help you to rank higher in SERP's, the words in filename are considered as Keywords (See the image bellow).
So give your Image a proper name that should consist of proper description containing keywords of the post for which you are going to use that image.
Image alt Tag(Most Important)
Use proper image title tag in image url as bellow
<img src=”your image url here” alt =”sample alt text here”/>Alt tag is the primary thing on the basis of which images are ranked in image SERP's. So select your alt text carefully and try to be descriptive along with blending your keywords in that description.
Title tags are not so imporatant as alt tags but they still are counted,so better to use them.
Title tags can be used in image url as follows,
<img src=”http://sample-url-here.com” alt =”sample alt text here” title=”sample title text here”/>
Dont StuffThis is basic but I am still reminding you, dont keyword stuff filename,alt tags and title tags. Let them be short, targeted and descriptive.
If you are spending hours to write your posts then dont feel lazy to optimize your post images. Remember these small things will only help you to beat your competitors. It is nothing but something like "Overtaking your competitors when they are sleeping".