One large misconception about rugs is: they cannot be laid on a carpeted area.
This is false. Layering rugs is the historical way to dress up traditional hardwoods and cold concrete to bring warmth and a sense of "welcome home" into the space. When layering rugs make sure that whatever floor cover exists it should remain to be seen. Rugs should be layered in sizes starting with larger scaled rugs, like area rugs first and layered from there. Same color family (complimenting) or just the opposite (contrasting), same patterns - different colors, Different patterns, truly the combinations are endless, all are options to bring dramatic flare to your existing floors. My favorite is layering rugs on hardwoods, it's glamourous and a great way harmonize your existing color palettes. I will share pictures shortly. Working on my Ipad.