What kind of climate? Is your budget for a bunch of annuals at this point, or will it be covering more plants and hardscape changes?

Building a lush garden takes years, a few things added each year and build in layers, like the layers of an onion. Have a vision for the shape of the garden you wish to achieve and make a sketch. I did a quick really rough one of your yard, how I see it, but I don't have any small children, so that is why I have such a big garden in your yard. LOL. My preference is for sweeping curved landscapes, that is why I preferred a curved natural stone fieldstone walkway to your shed. You can play with shapes of gardens by laying out the hose in the shapes you are trying out and then you can spray paint a line, or use lime for the outline. It is a lot of work to dig out the grass and edge, so once you have a plan, you could do a stage each year. I am still at it 15 years later here at my cottage. I would cutsie up your shed walls with Clematis vines on matching trellises each side of the door and Hostas in front of them. Maybe that is all you will do this season, maybe with a new curved walk way to the shed. Then next season, add one more section of garden and build to the plan each year. Fun! Good luck with your planning.

a little more info: I live on the east coast.

Duplicate post: https://www.houzz.com/discussions/looking-for-ideas-dsvw-vd~998251