When selecting a table napkin, the most important factor to keep in mind is the nature of the event. Use napkins that are suitable for the event. At a formal dinner paper napkins shouldn't be used, but paper napkins would be acceptable at a casual luncheon. At formal dining events, cloth napkins with a solid color should be used.
The standard size for luncheon napkins are 17" x 17" while dinner napkins are 20" x 20".
Napkins with firmly woven threads such as cotton or linen are best for folding as they will hold a crease and folds will hold better. Also lightly starching the napkins will also help with the creases and folds.