If you're feeling adventurous, carry a tape measure and check out the size and shape of furniture around you.
If you really start getting in to designing furniture "The Measure of Man and Woman" (http://www.amazon.com/Measure-Man-Woman-Factors-Design/dp/04...) is full of useful measurements and ranges that tables and chairs should satisfy for average, 1 percentile, and 99 percentile humans.
Wood is actually pretty forgiving. You can prototype the size of something in cheap pine, and remember, it's always easier to cut off another inch from those table legs then it is to add one!
If you really start getting in to designing furniture "The Measure of Man and Woman" (http://www.amazon.com/Measure-Man-Woman-Factors-Design/dp/04...) is full of useful measurements and ranges that tables and chairs should satisfy for average, 1 percentile, and 99 percentile humans.
Wood is actually pretty forgiving. You can prototype the size of something in cheap pine, and remember, it's always easier to cut off another inch from those table legs then it is to add one!