Tablescapes to me are one of those things that are "easier said than done." It is not that easy to make an interesting display that does not feel overly contrived. The best way to start is by putting out things that you like to look at, or items that you collect, whether it be books, art, sculpture, paper weights, plants, flowers, porcelain, etc....Then move things around until you have a composition that contains a balance in color and texture, and variance in height. The best way to get ideas is to look at what other people have done. All of the images here really inspire me.
Photograph by Gilles Trillard
The New Eighteenth-Century Style by Michele Lalande, Abrams Publishing, NY
If you are going to go monochromatic, make sure you vary your textures. The image above has a mix of paper, natural (sea fans), wood, and metal.
Design: Windsor Smith; Photograph by Victoria Pearson
I like when people put things under tables as well. And the way Smith layers objects even there makes this small little area very complex and interesting.
The way Roman mixes whimsical objects with serious ones makes this look super sophisticated. Leaning artwork/framed pieces is ALWAYS a good idea. It keeps a room from looking stuffy, and you can rotate things more easily.
Ok, this doesn't technically constitute a tablescape, but to me the painting is so close that it almost feels connected to the table, and with the sculpture in front, layers are created.