I've found that the most important step 1 in prevent blistering, losing toenails, and beating up your feet is to go to a shop (like REI) get your feet fitted to a proper boot, and have the sales person examine the fit. I did this before going on a 35 mile 3 day hike on the John Muir trail in Sequioa National Park. I went with three other guys, all of whom are avid hikers and all three had wrong fitting footwear for the hike. I was the only one who didn't lose toe nails and get blisters. I also use baby powder for my feet and preventing jock itch along with super glue for any bad cuts or severe blistering (I'll generally let the blister dry out, wash it, neosporene, dry, then super glue with some sort of bandaid over it). Second biggest step for me is spending the extra money on high quality merino wool socks or performance blended socks (depends on the hiking, distance, weather, etc). I usually hike around southern CA on the temp changes are the biggest factor when hiking out here, especially if long distance backpacking. Best bet is to bring a variety because excessive sweating in your boots will lead to blistering (unless you're stopping frequently, which will ruin the pace of your trip). Lastly, duct tape, hands down. I've used medical tape, hockey tape, electrical tape, etc while hiking/climbing/backpacking and duct tape is by far the strongest. If you need to use tape then bring along the kind that is multifunctional, it could save your life.
