Have you considered just improving soil in regular landscape beds? It would be simpler and better looking than doing raised beds.

You could do a lot of things with your yard. It looks to be a decent size. Right now it looks kind of uninspiring. Do you want to have more vegetable beds? Do you want to have more perennial/flower beds? Do you want seating? What is your garden style? You could divide up some areas depending on what you want it to look like or the purpose of space. But until you have a better plan overall; it's hard to suggest ideas.