Like others have said, get a passport for sure. It's about $125 and it's good for 10 years, not a bad deal. At border crossings, just be straight with them and have your papers ready. Get cocky and they can make you sit for hours or turn you away. People go over all day, everyday, no big deal, but do your homework. i would guess some bordertowns are easier than others. I just came back from Montreal with a 25' enclosed job trailer and it took all of 5 minutes to cross back. Try to pull a fast one and they can get you for it. Beer did cost a little more, but it's not worth the hassle of smuggeling more than you allowed. Heck, your there to hunt, not party all day right?
have fun and good luck!