If there is an REI store near you, go there, tell them what kind of hiking you will be doing, and they will (or should, anyway) do a good job of selecting and fitting you with an appropriate boot. I'm guessing your trip involves just day hiking, not backpacking. If so, make sure you tell the fitter that. It means you can be fine with any of the lightweight trail footwear. Lightweight means less fatigue for you.
REI will let you return boots even if you have worn them outside. My favorite pair of boots for backpacking is a pair I picked up on the "discounted because they're used" table (though they still looked like new). Also saved big bucks on a Gregory pack that had obviously been used but still had a lot of life left in it, and it even had the different size hip belt I needed!
I never wear two pairs of socks anymore, whether for day hikes or loaded backpacking. As Pat_B said, socks have come a long way. My favorites are some Smartwool socks and some REI socks, both wool-based but with synthetics engineered in. The only thing I vary is the weight (thickness): lightweight ones for day hikes, heavier ones for backpacking.
I'll go against the tide here on the "break 'em in" theory: properly made and fitted footwear should be very close to being "just right" the minute you walk out the store. This is particularly true with the mostly-synthetic footwear, which isn't going to change as much as an all-leather boot. Another way of saying this is, if it doesn't seem right when you're trying it on in the store, it probably isn't going to get better later, and you're going to have problems. That said, it is still a good idea to get them well before the trip, just to have some time to wear them to find out if there are any fit problems.
Biggest cause of blisters, after wearing cotton socks, is poor fit around the heel - usually too loose. Looseness allows the heel to slide up and down too much>friction>heat>blisters. Cheap and dirty solution if you're stuck with it: duct tape. Yup. Put a duct tape patch on your heel (or wherever) as soon as you have a clue that there is a problem. The duct tape becomes a second skin that slides easier than yours and can take the wear and tear. I've found it works much better than moleskin.