Beware broad-brush approaches, even if you find a dictionary offering the count – uncount classification. Some – perhaps many – nouns are non-count in some senses and count in others. Coffee is a good example – its basic sense is uncount:
Coffee is a drink made by infusing the ground beans of Coffea arabica
Too much coffee can be bad for you.
However, different products will be count:
Coffees produced using a higher proportion of robusta beans in the
blend tend to be bitter and have less flavour but better body than
those with a higher proportion of arabica beans.
And ellipsis produces another count-noun polyseme:
Two coffees, please.
(ie two cups / mugs of coffee)
Rice is count when different strains are meant, and sand when different sorts are being mentioned. (There is a poetic use of sands also.) Even furnitures is allowed in certain situations.
There are also grey areas – you'd probably ask for less peas rather than fewer peas (especially if they were mushy) on your plate. Non-count doesn't always mean that counting would be impossible - confetti is treated as a singular non-count noun. The difficulty ensuing when one tries to use algae in both count and non-count senses has recently been addressed in a different thread.
A good place to start looking is http://learnenglish.britishcouncil.org/en/english-grammar/nouns/common-problems-countuncount-nouns .