I would probably go two or three shades lighter staying in the same sage green family, or use a cream and water it down so that the original sage color shows through.
Having Sage Green Walls In My Living Room. I Would Like To Lighten It Up By Wall Sponge Painting, What Color?
If you are using a sponge try gold glitter dabbed throughout the space.
When choosing colors, you need to consider the color scheme of the room, the color of the floor should be appropriate in the design of the room. In order for the floor covering to look more interesting, you can make a drawing on it, which can have a different degree of complexity, geometric patterns and prints (the easiest option in terms of performance). For those who are interested, here is a link to a good article on the topic - http://bord-eaux.com/general-tips-for-the-home-interior-design/