- Replace graphical elements with CSS as much as possible. If you have a bunch of graphics being used for gradient backgrounds, rounded corners, shadows and such, these can all be done with CSS and the effects are pretty consistently supported in all major browsers these days.
- Also, for other graphical elements, if you are using PNG's or JPG's for things like icons or logos, consider swapping them out with SVG images or creating a custom icon font with Icomoon.
- If you are using graphics for fancier text in a unique non-web safe font, consider replacing those with actual HTML text styled with one of the many free Google Web Fonts instead.
- If your site is running on Wordpress, there are a number of caching plugins available, but I would say W3 Total Cache is perhaps the best of them. It's also the most difficult to configure though so check with your web host if they offer a config file for you.
- Consolidate your tracking tags, and remove the ones you no longer need. Too many tracking codes on your site can slow it down dramatically.