I always take an X and O chart, and color it in..
use colored pencils (my favorite) or color hi-lighters (that you can see through), or even water color paint or water color markers (again, like hi lighters, clear color)--regular markers are too opaque. (for my taste--but you might like them)
i like pencils, cause they come in the largest range of colors, and i like to use colors close to the actual yarn color..
make a key for your self if needed -if the pattern has 3 shades of blue, i often make Lt blue, grey, dark blue--instead of straining with Lt, medium and dark pencil colors.
this preplaning pays off.. an hour spent fixing up the chart often is many hours saved (from frogging)