I don't go into too much detail (on the grounds sending readers to sleep is generally not a good idea or a reflection on the writer!) but I give enough so people can form their own mental pictures. I often see very nice picture images on Facebook and write down a description loosely based on it and set it in an area in my creation that does not marry up directly with a suitable area.
Conveying smells can be difficult in fiction. I tend to compare a spell with something else. Again my idea here is to conjure up and then flesh out. Taste is probably the easiest sense to convey in writing. There is always something you can think of and if it makes you go "yum" it should have the same effect in the readers.