I'll chime in here. I started working in the outdoor industry in small shops ten years ago. I've had a few different fit system clinics in that time.
Number one, as stated, is your socks. If you go with a good pair of Smartwool hiking socks, you should be good to go from there. There shouldn't be need for a pair of liner socks, just change your socks daily when you're out, wash them when you can. Smartwool's are made from merino wool which has a longer fiber than traditional wool. It is then chemically washed/treated to make the fibers smoother. The knitting process gives it that pleasant feel and provides necessary cushioning. I've sold thousands of these. I've also heard Bridgedale makes a good sock, but never been able to get my hands on a pair. Wool dries from the inside out versus cotton that dries outside in. Synthetics just feel like, well, plastic. One of the big things being looked at right now is how much better traditional fabrics perform over even todays best man mades. In fact, keep an eye open for the Mallory/Irving recreation expedition. They think that the clothes those guys were wearing might actually have been a lot better than had previously been give credit for.
Step two, find someone who knows how to actually fully use a brannock device!!! This is the hard part. Knowing how to use one and what to look for on a foot are indespensible. A good fitter will measure the length and width of both feet. They will also look at your arch, your foot volume and look your foot over for oddities such as heel spurs and the such. They should then be able to use that information to translate over to their shoes and boots they carry and possible modifications that might need to be made in insoles, lacing tricks and maybe even a stretching bar.
Don't be afraid to try a lot of shoes on for a long period of time. Also try different insole systems like Superfeet or Montrail if they'll let you (they should). When you think you have found the perfect combo, take them home and wear them inside the house for a while to see if anything feels weird.
Your mantra during all of this will be: Anything that bugs ya' even a little now will amplify a thousand times over when you're in the middle of nowhere!
All that being said, realize that all the stability and support you get out of a shoe, comes from the sole and insole. All those fancy high top boot cuffs that salesmen are going to tout for exeptional support, can be easily flexed by eventhe weakest hands, even my Koflach double plastic ice climbing boots. The support they offer is placebo, what they do do is protect your ankles if you're hiking in a rocky area, like a scree field.
Unless I'm climbing somewhere that I'm going to need my crampons that require special welts for my bails, I wear stout trail runners, gore-tex ones if it is going to be rainy. You would better serve yourself doing some strength training for your feet, ankles and calves. Heel raises, barefoot running and walking, agility drills, alphabet writing, towel scrunches.
Hope that isn't too much.