Bring only what's on the required and recommended lists. Get some XL (10 gallon) ziplock bags from Walmart/Target and put everything that you plan to bring, except boots, in 4-5 bags. You can put these bags in a duffel bag (or backpack if you're bringing fewer things). Early on in the day, after you check-in, you will have to transfer everything you've brought into the issued bag and carry that bag around, along with more clothes and other issued items. You can hang your boots on your duffel -- wear your low quarters when checking in. You'll be issued (if like last year) another pair of boots and low quarters, so the more you bring the heavier your bag will be when you carry it around all day.
Heard stories from last year's Beast that some new cadets that didn't have their items in ziplock bags couldn't transfer items fast enough to the issued duffel and then weren't allowed to take everything. Make sure your cell phone is an a ziplock watertight bag; it will be stored until the end of Beast.