Start by planting some annuals and periannials that make nice cut flowers. A couple of great annuals are gerber daisies and zinnias. Shasta daisies, brown-eyed Susans and day lilies are very hardy periannials that will spread so give them lots of room. Dahlias are very hardy as well, and a lot of them get quite big. My MIL used to raise them, and had every sort you could imagine.

Don't forget your spring bulbs like dafodils and tulips. You'll want to plant them in the fall before the frost.

Lavender is another great periannial that you can use to fill up some of the space. It spreads as well, and can become woody after a few years so it might need to be dug up, and replaced. That's what has happened to mine so it's time for new start.

Go to your local nursery and ask what grows well in your area. They can help you with soil prep, and other tips and hints to make your yard beautiful.

I had a similar dilemma. I went to a nearby, family owned nursery. They came out looked at the site, measured, and listened to what I wanted. They made a plan based on my likes of colors, plants, and amount of care that I wanted to provide. They gave me the choice of doing the work myself, or they would do as much or as little as I desired. They stand behind their plants. I had them put in everything because I am retired and prefer to garden vegetables. I considered my landscaping as an investment in my property; one that would increase it's value. I'm very satisfied. I would do it again:)

It would help to know your planting zone. I agree with Sandydavid, your local family owned nursery can offer expert advice sometimes for little to no cost if you buy all your plants from them.