I would work VERY closely (if at all possible) with their classroom teacher.
Try to integrate every chance possible since not only does this aid in their
learning, but it will also make your planning abit easier. Our kindergarten
teacher uses Animated Alphabet and I plan my lessons around their letter of
the week. She also works with alot of themes and this also helps with
ideas - for instance, when they are doing their cooking unit (always around
December) then I bring out gingerbread scented playdough (since I spend more
and more time focusing on the experience than the product I am more flexible
with their materials).