I actually work out of Gettysburg, but like most of the locals I try to avoid the tourist areas and unfortunately I don't take advantage of the history in the area like I should.
There are some private companies that give guided bus tours of the battlefield. I think they all load and unload at the tour center in Gettysburg. They depart like every hour or something (the tour takes a couple of hours), just buy your ticket and jump on the next bus.
If you are driving and have your own vehicle I would suggest taking the self guided auto tour. Stop at the visitors center first to collect some literature and drive your vehicle on the self guided automobile tour. There are signs and maps that will guide you around the battlefield and point out important things. The self guided driving tour allows you to stop when you want for as long as you want. Unless you are a really social guy who just needs to be in strangers company, self guided is really the way to go. There are also several points around the battlefield where rangers or historians will discuss specific events if you are interested in the details.
Make sure to visit the national battlefield visitors center first thing because that's where you will get all the good literature and where there are park rangers to answer any questions. They also have films and presentations at the visitors center (for a fee) if you want to attend those. The visitors center is pretty new, my wife and I went there a few weeks ago. We hadn't been through the battlefield for three or four years and the visitors center wasn't there three or four years ago, that's how new it is.
Even though you will be driving, wear good walking shoes because there will be lots of times you will want to walk around the monuments in the park, go up in the observation towers and check out the town. Plan on spending some time walking the streets of Gettysburg as well as on the battlefield. The town is full of history and shops and good restaurants. They have ghost walks pretty much every night if you are into that kind of thing and are there past dark.
There are also bicycle rentals and tours if you feel like doing that, I'm not sure what date they start renting bikes though. There is also an air tour company that flies you around the battlefield in a helicopter if that floats your boat.
I would suggest going to the National Park Service website, searching Gettysburg national battlefield and start there. IIRC they have schedules for various talks and educational programs, they also give directions to important places and so forth.
If you are visiting because you have a historic interest in the civil war, you may as well take a day and drive south an hour or so to Harpers Ferry and the Antietam battlefield. Lots of history and more interesting stories in that area (IMO).
STUPID IS THE NEW NORMAL