Optimize loading time of my website

I want to optimize the loading time of a website i've got Google pagespeed gives me 84/100 YSlow gives me 74/100 Need a way better improvement as well advice if to change some images, for example the background image is messed up as well as the footer image is a png and i think could be better as a jpg image both are like 250KB between both out of the total 700Kb of most all the pages in the site PM me in private ill give you the site and you can give me your opinion if you can improve it a lot or not Need people who have done this in the past