Know the parking plan arrangments. Likely you park off site and get shuttled in. Time and plan accordingly. It can add up to an hour to and from parking to course and back to parking.
I like picking out a set of groups you want to watch (usually they are 4-5 good ones bunched in both morning and afternoon), and stake a good spot a few groups ahead of them, and watch them all play from that spot. This is good to do if you plan on sitting in grandstands, which can get crowded, even moreso on Sunday.
As stated, there will be lots of walking, including getting to and from the course. Comfy shoes are a must. If rain in forecast, waterproof ones a bonus.
If you're hitting merchandise tent, go after Tiger has teed off 1 - that'll reduce the crowds a bit.
Check the bag rules on PGA website. Usually no bigger than rucksack, and might require see through. Bring the sunscreen and bug spray if that's potentially an issue.
Don't be ashamed to watch some of it on TV on the course, as there will be good sized crowds around such large screens taking in the action while they eat and drink. Can be a fun evironment.