How can i improve the loading speed for my Wordpress Site

From one of my previous conversations with i understand that there are ways to improve the loading speed of a wordpress site. We have completed the design of a WordPress site but I am not sure if our developer has carried out all of the activities that can be used for improving the speed of the site. I have heard that we can

• Install supercache plugin
• Remove unwanted/unused files that are part of the WordPress CMS

Are these the only things that should be done?

How do we "Remove unwanted/unused files that are part of the WordPress CMS "

What assistance can you offer?

Do you have anybody that can do a review for me?