” …you can take the first draft of any poem and improve it 80% by lopping off the first and last stanzas.
“… with the first stanza we are struggling to get the creative juices flowing; by the end of the poem we are so enamored with what we are doing that we don’t want to stop
“… what do we agonize over most when writing a piece? The first sentence, the first paragraph, the first scene. Jump in, don’t worry about it; assume you’ll throw this part out when you revise, anyway.”
— John Lehman, Like Melting Ice, quoting an observation by Rod Jellema
Taking this into drawing and painting, I think it is: jump in and start anywhere; include less (in the composition and detail); stop sooner.