being in the habit of buying yards at a time myself, i can offer lots and lots of sympathy.
don't let it dry all the way. take it out of the dryer while it's still just a leeeeetle damp.
lay a clean sheet down on the floor and put the ironing board in the center.
puddle the fabric at your feet and "feed" the ironed sections over the back of the board. if you iron them dry, don't worry about a few new wrinkles when they hit the ground on the other side. those wrinkles will probably get smoothed away while you fold it - which is going to create wrinkles anyway so there's no point in worrying about it too, too much.
once it's all ironed, drape it over a bed with equal lengths dangling over the sides. start at the middle and fold selvage to selvage, working your way out toward one end, then toward the other. smooth it as you go to keep the fold flat and smooth.
repeat the process to fold it into quarters lengthwise.
get a nice, stiff piece of cardboard ... about 8" x 12" or thereabouts.
start at one end, and roll the fabric onto the cardboard. when it's all rolled up, pull out the cardboard to use again. it'll stack neatly on any shelf. AND when it's time to cut into it, you can just unroll what you need. AND it's folded nicely for easy rotary cutting on most size mats.
:D