You'll need a promo kit at the very least. Some larger companies will want album sales or a list of venues you've played at.
Usually, unless you're a bona-fide 'star', the sponsorship deal they offer will be nothing more than a discount on future purchases in return for advertising.
Get legal representation & keep in mind that if you're in an upcoming band, you may want to wait until you're in a better position to bargain before signing any contracts.