I love gardening.
DNMommy - it helps to read how to take care of whatever before you attempt to grow it
I am sure you don't have a black thumbs, just inexperienced thumbs - don't give up yet
And cacti, contrary to popular belief, are not quite as super easy to grow as it would appear.
True, they like bright light and plenty of it, but
on the window with full sun and all day they MIGHT be scorched (burned)
and some do get frost damage in winter.
they catch pests and diseases just as any other plants.
yes, they might be over-watered but sometimes over-watering is mistaken for
rot, a fungal infection at the bottom of the roots.
they might be also underwatered.
Why don't you try this wonderful houseplant now:
Epipremnum aureum aka Devil's Ivy aka
Golden Pothos
this is the easiest house plant under the sun to grow. It likes moderate to bright light which mean close to any or on bright window (morning and then late late afternoon, no noon heat is best)
they do not do well in direct sunlight
and although it will happily grow in the shade, too, the lack of adequate light will cause loss of shading on the leaves - but that is all that will happen. no biggie.
It's a trailing plant which mean the stems will grow and grow and grow down- which you then may support throughout your house with strings or long sticks. they could be trained to go up, too. best to grow it in a hanging basket.
if you wish, you can trim the stems to keep it smaller and bushier. put the cut stems in the water - they'll root easily!
How to easy water - water as soon as the soil on the top in the pot is well dry to the touch.
Pothos like to have their soil dry out completely between waterings. be careful, though, as soon as you see leaves drooping promptly water the plant.
Fill the pot to the brim, wait for the water to drain then soak back from the saucer as much as possible,
then discard the excess from the saucer away. repeat until next time.
remember - in the spring, summer and early fall water more often, late fall, winter (the rest period) water less often.
(you will know it)
Once a month you may want to give your Ivy a feed of this fertilizer - is super easy!
http://ecx.images-amazon.com/images/I/51eZ95o2nyL._AC_UL320_SR200,320_.jpg
more info about Pothos:
http://gardening.about.com/od/specifichouseplants/p/Pothos.htm
and good luck! or, should I say - green luck !