Now here's a big factor for pitchering. The weather here ranges from 20-80% humidity depending on the time of year. I do get some coastal fog during the summer mornings and evenings that tends to keep the highlanders a bit cooler and increases relative humidity. Keeping the soil media moist also aids in pitcher development. 

My biggest revelation for pitchering was hosing down my plants at the end of the day. I hand water all of my plants and don't employ a misting system so my Nepenthes were growing on the "dryer" side so to speak. When I started hosing them down once a day during the warm months, my Nepenthes began producing larger, more numerous pitchers constantly. I also discovered that the pitchers would fill with water and not have their enzymes evaporate. This allowed for longer pitcher life and the opportunity to catch more insects because the traps were filled with water. The top part of the soil that usually was dried out from over exposure to the sun started growing again, too. Nepenthes that almost never pitchered began producing traps profusely for the first time in years. So I've become a big proponent of misting or hosing down Nepenthes.

Keep in mind that hosing down Nepenthes doesn't replace watering them. I still water with R.O. or reverse osmosis water and hosing them down only increases humidity around the top part of the plant. My hose water is city water and is on the hard side that does leave traces of white "chalk" residue on the leaves. That is unavoidable for me since I don't have R.O. water to spray them down with. However, the Nepenthes don't seem to mind it at all and has had no adverse effects. Even the pitchers that fill with the hose water last longer and are filled with bugs so the Nepenthes appear to be very tolerant of less than optimal water. Once again, I'm not advocating using city water on Nepenthes. Always use the best water possible for optimal growth. But for me, this works and the Nepenthes benefit far more than from not hosing them down. 

For my lowlanders indoors, they are generally kept in more humid conditions. They do like to have a little misting once in a while so I'll do that on occasion. All Nepenthes appreciate a good spray as long as they're not being soaked and kept extremely wet for periods of time. In the winter months, I don't hose down as often since my Nepenthes aren't actively growing as much. The added moisture could lead to rot that is my biggest problem outdoors. 

Finally, ask your vendor how they are growing their plants. Vendors that have taken the time to acclimate and harden off their plants will have excellent advice. Plants recently imported or fresh tissue culture plants need time to acclimate or they can be very susceptible to stress. I've found that whenever a vendor has had plants acclimating for several months before selling them, I have had virtually no problems adjusting the plants to my growing conditions.