it is said that watering them with rainwater is good, and a feed every other watering. Let them soak in water, BUT not for too long, once they've had a good drink, drain them off. Also standing on a tray of pebbles above water can help them not dry out too much.
But - my boss has some lovely ones that have sat in a south-facing window in full sun (in south of france!) where they get toasted most of the year - with a short burst of cold - they have survived for years!!! So go figure...

In my experience, the most common mistakes that people make are keeping them too dark, and overwatering them. In their natural habitat, most cultivated orchids grow on tree branches, reaching for the sun, drying well between rainstorms, and hoping for a little dust or dead bugs for nutrients. Humidity is good, but most only need levels that people are comfortable with, around 20% to 40% relative humidity--it probably only needs serious attention in the winter, unless your heating system includes a humidifier. Since most folks frown on bugs in their houses, occasional light feeding is helpful, usually with a formula with 2-1-2, or 3-1-2 proportions, preferably with no urea, especially on Phalaenopsis orchids.
In the florists and garden centers, there are these very pretty displays of orchid plants stuffed into glass vases, but they cant last more than a few weeks, there. They're better off transplanted into pots with excellent drainage, in a medium composed mostly of bark or coconut shell chips.

I have five orchids and didn't ask for any of them but inherited them from relatives and friends who couldn't look after them! When visiting my dentist last year, I commented on her beautiful orchid blooms and she told me she had over 100 at home. She advised me to put them in the sink filled with water and leave to soak for an hour, then drain - once a month. I now have all five about to bloom, most with two flower branches. If I can, anyone can! I'll post some pics in a few weeks. P.s. Mine live all year round on an east facing windowsill.

Thanks Cammomile, that makes it sound so simple! You can read a book and it gives all the correct names, how many times to feed and water and you go into a daze with glazed expression. I have about four which I have managed to keep alive - not full sun, not too much water and ignore them apart from admiring them. All I have to do now is decide when and if they need re-potting and do they really need a clear pot?

I havent much of a clue about pots apart from the fact that I have the clear ones and read that it's something to do with bacteria? They do however stand in ceramic pots.