Check out
the link. This site is a mess and you have to sort through it, but there is a lot of information. The guy has a lot of information about how holdback works and how dealership price the extras they offer. In short, you should be able to get more than the discounts that they are advertising. These are manufacturer discounts, and don't cost the dealership a thing. This means the delearship isn't really charging any less than MSRP, which is a crappy deal. Basically, you need to do the following:
1. Figure out the invoice price of the truck and the holdback percentage (refer to the site above)
2. Use this to make a reasonable offer that will most likely be below what the dealership is suggesting
3. Have all your ducks in a row so you know what you're talking about when you visit the dealership
4. Don't let them charge you for stupid crap like pin-striping or fabric protectant
If you are really concerned about getting the most for your money, you shouldn't trade in your current vehicle either. Dealerships make tons off your trade in. On the other hand, there is a sales tax benefit for trading in. So you have to work out the numbers, but generally you're better off selling it yourself. If you plan to trade in though, do your research so you know what the car is worth.
I should warn you, the site above has a ton of information that could take some time to read through. But, I think it's definitely worth educating yourself, especially if this is your first experience buying a vehicle.