Strive for Symmetry
You may have spent a fortune on crystal and fine china, but expense is no guarantee of a lovely table. For that, you need to create symmetry. Sure, spending a lot of money on coordinated tableware makes the job easier, but it's not the only way to make your tablescape look great. When you think about the beautiful table designs you've seen in the past, symmetry is one thing they all have in common.
Symmetry in design is never an accident. Whether you're achieving it with precisely repeated stacked or fanned items, or eyeballing your placements and using experience as your guide, creating and repeating patterns is important for good table design. If you don't have enough of one china or crystal pattern, you aren't necessarily in trouble, either. You can alternate two similar patterns and pull everything together with your candles, centerpiece or tablecloth.
The secret to creating a beautiful table is to audition your elements beforehand to see how they'll work together. You may have to try a few different layouts before you find one that works. The last thing you want is to be so rushed you're trying to chop salad greens and set a fancy table at the same time. From the napkin rings to the salt cellars, assemble your materials and play with them until you find a combination that works. When you've achieved a nice balance, you'll know it.