Seriously - I'm NOT good with plants if the require any kind of special attention. I can't keep African Violets to save my backside and I just gave up on them! And regular cactus - forget it! The "Thanksgiving/Christmas/Easter" cactus pretty much take care of themselves for the most part. I have a Prayer Plant that I think will outlive me, and it's already about 25 years old. I over water-under water-leave it outside when it gets too cold, and that sucker just won't die. It looks like it's dead and I cut it back to nothing, and it comes back looking better than ever! :p
Your cactus probably doesn't get enough sun. I have mine in the same front window as the orchid, so that must be a good place and the right amount of light for both of them. A few years ago, about 1/3 of the plant died off, but I think it choked to death! :eek: We were having some renovations done to the house, and there was a lot of dust from the drywall sanding - I never thought to cover the plants.
This pic is a couple of years old - it's a lot bigger now.
My SIL saves water that she uses when cooking veggies, since so many nutrients boil out and into the water. She uses this to water her plants.