In addition to choosing tables and chairs of compatible scale, the pieces need to look good together. The styles must be compatible too.
Choosing tables and chairs with a common element usually ensures that they'll look good together. That common element can be the period, the color undertone of the finish, or the level of formality. It can even be a single design element, such as the furniture legs or feet. That said, don't choose tables and chairs that share all of the same elements or you might as well just buy a matching set.
If you have an 18-century mahogany double-pedestal dining table with a gleaming French polish and you want to pair it with distressed pine ladder-back chairs with coarse rush seats - your design won’t be in the same style. The choice of such a table will also differ in style from a collection of metal ice cream parlor chairs or folding French garden chairs made with wooden slats.
A planked farmhouse table with turned legs is the better choice with any of the chairs from the previous paragraph, and mahogany table will be ideal with the Chippendale ribbon-back chairs.