This applies to all boots, but one thing to check before even trying them on is the insoles. This is my #1 annoyance with just about every boot made these days from $50-$500 they almost all come with thin junk insoles.
On the face it seems like no big deal, you go spend $20-40 for a good insole, but it's a double whammy. In most of these boots the included insoles are very thin with no support, cushion, or heel pocket. So the boots have a lot more volume than they will once you replace the insole with something of quality. So not only does the factory insole suck, but you have to keep replacing it with another crappy thin insole in order for the boot to still fit properly, or deal with a boot that is now too tight front of the foot, and possibly too tall in the heel changing how your heel fits into the boots heel pocket. Plus, it's actually hard to find replacement thin insoles.
That's the real problem, boot companies design the fit/cut/width of their boots for those thin crappy insoles so when you replace them with something of quality, you've completely changed the fit of the boot both in the volume and heel position.
I learned this the hard way with a pair of Meindl Alaskan boots, great boots but the factory "air" insole is worthless. If it's not bad enough that a $300+ boot comes with a $0.25 insole, once I put a real insole in them that had support and cushion it took up way too much room in the boot so the boot was not wide enough up front, and it lifted my heel enough that heel blisters resulted. Only option was to continue using crappy thin insoles with poor cushion and support.
I understand companies do it to save money, but at least put a cheap insole in there that has some thickness to it so that when you replace it the volume and foot position stays approximately the same. Frankly companies like meindl, lowa, scarpa etc. should be ASHAMED they are putting these insoles in boots costing hundreds of dollars. Add $15 to the price of the boot and include a good insole to begin with! A good insole can take a mediocre boot and turn it into a great all day boot, you'd think companies would want that for their customers.
In fact I've had high end lowa, la sportiva, meindl, danner, merrell, scarpa, etc. boots and the only pair so far that came with an insole thick enough so it was similar fit to a good replacement insole was my Danner combat hikers. It was still not a good supportive insole but at least it was similar in size so the boot fit the same when it was replaced.
Take along a good cushion/support insole with you when trying on hunting/hiking boots along with a good pair of medium cushion socks, or whatever sock you plan to wear. Even if it's just a cheaper insole that's 3/16" thick or so to mimic what a quality superfeet, sorbothane, sol, etc. insole will. You'll also be amazed what a good supporting insole can do for the support and hiking stability of a hunting pac boot like the Schnee's as well.
Don't be surprised if once you start putting a good insole in boots before trying them on that they don't have enough room in them, in most boots with a good insole even normal width feet have to go to a wide size.
The best procedure I've found when trying boots on is this. First take the insoles out then put your bare feet in them without socks on. This really lets you feel how the last or flat base of the boot fits the shape of your feet because the insole can mask how the shape of the boot last really fits your foot. Then put the insole in and do it again. It's so much easier to tell if it's going to rub your toes, too narrow, not enough/too much arch, heel way too big not big enough or a heel pocket that doesn't fit without the sock on especially a thicker hiking sock. Then do the same thing with your hiking socks on, see if any areas got too tight when you added the sock. A good general rule is if you slide your sock foot all the way forward in the boot unlaced you should just get your index finger between your heel and the heel pocket of the boot. If that all still feels good lace them up and wander around for 10-15 minutes in them, stairs or an incline board will tell you very quickly if they are going to give you heel blisters, but just walking on flat ground will tell you almost nothing about blister issues. Then kick the toe into the floor repeatedly to see if you can make your toes hit the front of the boots at all, which you don't want as you'll end up with black and blue toenails on long downhill sections especially with a pack on. It's also not a bad idea if you are going to be carrying a heavy pack to simulate that, the extra weight will flatten your foot out making it longer than without a pack on, especially if you have high arches. If they pass all that you are doing really well and the rest you won't find out till you get a lot of miles on them. Many boots won't make it past the bare foot test right off. It's a lot of work, but boots are too expensive these days to go buying them without doing as much as you can to ensure they really fit well.
The above might sound like a rant and too much work, but I have notoriously hard to fit feet (wide front foot and narrow heel) and I've gone through a ridiculous amount of boots to find a couple that fit well, but the above now lets me eliminate 90% that won't right off the bat.
As an aside if you have a boot that fits well but just gives you heel blisters take a look at the Engo patches, they are similar to a teflon like sticker that adheres to the heel of your boot allowing your heel to slip without blister causing friction. I've used them in a couple boots I liked but could never remedy heel blisters with by any other means. The only downside to them is once you use them you have to keep using them, you can't remove them without leaving sticky residue on the inside of the boot, for me they last about a year of frequent hiking and are pretty cheap. They've saved a couple pairs of boots from being worthless for me in the past, but I think of them kind of a last resort.