It's important to remember that each person has their own methods, and different things work for different people. That said, I've got two specimens of this species. I grow them both in regular room humidity with the same clamp-on grow lights and spiral fluorescent bulbs rball described. When I first started, low light levels caused my plants to stop pitchering for a while, but when I increased the light the pitchers returned in full force.
Soil: Long Fiber Sphagnum Moss. You can use this pure or you can mix in something like orchid bark or perlite. Do not use anything with miracle-gro or fertilizer.
Water: Distilled, reverse osmosis, or rainwater. Top water them when the top of the soil starts to dry out and never allow them to dry out completely. On the other hand, you also don't want them to sit in standing water. Damp but not flooded is what you want to aim for.
Temperatures: This variable is important for some of the more difficult Nepenthes. However, N. ventricosa is generally not difficult and should be fine in regular room temperatures.