There are many ways to go about what you want to do, but there are only a few ways to maximize your efforts. First, list out which schools you really want to attend for grad. school. Contact the coaches at those schools and inquire if they have a GA spot. If they don't have a GA spot available, ask if they are willing to take any volunteer coaches on board. Most teams have at least one or two volunteer coaches each year. While being a volunteer assistant wont pay for school, you will still get a lot of experience and make some great connections.
Also, don't be afraid to use your coaches contacts. That is sometimes the only way for you to get a position anywhere. Unless you are an all-American runner, it is all about who you know...just like most things in life.
Check out two websites on a consistent basis as well:
NCAA Jobs -
http://ncaa.thetask.com/market/jobs/browse.php
USTFCCCA -
http://ustfccca.cstv.com/ot/ustca-jobs.html
However, don't rely too much on those job postings. While posting for GA and assistant spots come about in late spring, the search begins way before that.
Last bit of advice...if you want to coach DI you will probably have to start out being a volunteer assistant. Start out at whatever level you want to coach long term. If you want to stay in DII then coach at DII. So, contact coaches on your own, have your coach contact coaches, and try to set something up by winter break. That's how the game is played.