several boxes representing each screen
each box is linked together by lines for the user flow
each box contains
basic screen layout with a title, swiggly lines with an arrow pointing to the swiggly lines saying 'text box or label with user instructions'
rectangles for command buttons
and i usually chuck in a few arrows pointing at a blank area of the screen saying 'non contrasting colors', 'images that do not detract attention away from the important features', 'ergonomic placement' and 'sans serif font'.