I used to throw ratchet straps into a big canvas bag as soon as I pulled them from whatever load/barge/water slide thing that I had just unloaded/disassembled/taken down. Of course they'd tangle immediately. A long time friend and construction worker told me one day, "Yep, that's just how those things are," as he showed his bag crammed with 30 pounds of tangled ratchet straps.
Step 1: Simply Wrap Them Up!
Leave the ratchet open (you probably just got done pulling the strap out of it, so it's already in position).
Lay the strap, hook side opposite the ratchet hook, on the ratchet.
Begin binding the two parts together.
The finished thing looks like a cocoon, and keeps the hooks from grabbing at other straps - never untangle a ratchet strap ball again!