1) Let them run and be free - lets face it, we all need a break, and some studies show that exercise prior to homework actually helps stimulate parts of the brain to be more receptive to information.
2) have them sign an agreement - they can do X if they promise to do Y first, and then hold them accountable - trust is super important and a valuable part of the relationship they have with the parent.
3) Have them utilize the rainy Saturdays with schoolwork, so the sunny day that follows can be spent outside without fear of a late or missing assignment.
4) Even though we have been in school for many months, homework can still overwhelm us - get organized and have a game plan. not only is it a great skill to role model, but it is one that they will be able to call on time and time again! (maybe work a few breaks to help them refresh and refocus from time to time.)
There are also a lot of great resources on the web that can lend a hand if you get into a sticky spot...here is a great one from a neighboring state.....
http://www.educationminnesota.org/en/community/studentsuccess/homeworktips.aspx