I create them as gifts for my own friends, and in a few cases I even made some for money, as gifts for someone else.
They may be very plain, like the one below, on the left (which is basically "white on white", no extra effects) or more elaborated like the one here to the left, or anywhere in-between (just a colored border, for example, as shown below, middle picture).
As a rule, I supply a small tag, glued on the back, to explain the meaning of the kanji.
Watercolor (the Western kind) on special Sumi-e paper.
The writing on top:
杜若 / 似たりや似たり / 水の影
is a Haiku by Bashō.
It reads, more or less:
Iris! / how much it resembles / its reflection in the water.
Apparently Basho was making fun of some other poem which reads:
Behold, how the Kakitsubata resembles the Ayame!
(Kakitsubata - Iris levigata - is the so-called "rabbit-eared Iris" which grows in damp areas, while Ayame is Iris sanguinea, grows in more normal terrain and - exactly like "Iris" in the West, can be a woman's first name).