All of the characters I draw are taken from photos. It’s convenient and favours the ‘surprise’ element.
When people request a caricature I require some good recent images of the subject and a description of interests, pastimes, hobbies – even work-place situations. This is a way of building the character into a fun representation that says “You are unique & special.”
Generally, an A3 size works well if props are included.
I use quality watercolours and w/colour paper or ink if a line drawing is preferred.
Don’t supply photos of person wearing hat & sunnies – it has happened.