A tea-length skirt should stop at mid-calf (between knee-length and maxi). Vogue makes a point of saying the skirts should be mid-calf to upper ankle.
This can be hard to wear. One trick to help it is wear with long, lean pieces on top. A tea-length skirt can look a little 1950's if it has the cinched waist.
If you are shorter, the problem may be in the proportion - there may be too much fabric in the skirt - if you take the skirt in on the sides, it may work better for you so there isn't so much volume. For any height, don't have too much volume in the skirt because it's going to make you look like a triangle.
If you are tall, the issue will be finding a tea-length skirt that's long enough. If you have a maxi dress or skirt from last year that you weren't crazy about, try taking it up. If you hate to sew, iron it up using Stitch Witchery. Pin the hem, iron the living heck out of it, make sure it is correct, then put the Stitch Witchery in between the new hem you've ironed. Then iron again according to the directions for the fabric. You may have to cut some of the excess hem off before you iron up the hem with the Stitch Witchery or else it will pull down. Use pinking sheers so it doesn't fall apart.
A subtle wide belt around the waist works well or just layering over a thinner skirt. The point is not to have too much bulk. The whole macro view is what you are going after so don't over accessorize.