1- Optimize your images
When you create your images, save it in the smallest form possible without loosing much quality. There are also tools to optimize images after the fact. WordPress also has some plugins that allows you to optimize all images of your website
2- Get rid of extra code
3- Use a CDN
What is a CDN? it stands for Content Delivery Network. It is a service that stores a copy of your website on hundreds of servers over the internet and serves a copy of your website to the user that is closest in location to them, hence resulting in a quicker load time. Not only this is beneficial in speed optimization, but also CDN’s give you protection against hacking and denial of service attacks (DOS).