Rules of thumb for most cacti and succulents:
1. Light: As much as can be provided. However, contrary to popular belief, most cacti detest scorching heat. So bright light in a normal temperature (60-90F) environment is good.
2. Watering: This depends on your environmental conditions. Rule of thumb is to water only when the top 1-2" of soil is dry. When you water, do it thoroughly and try to do it in the morning so that the soil is not totally wet overnight (promotes rot). I sit my pots in water for 10min so that all the soil is wet. When finished, make sure there is NO water in the saucer or you'll get rot. Most cacti like some sort of winter dormancy (not usually required to live, but it is for flowering) during which they prefer to be watered much less.
3. Soil: Any very loose and well draining mix will do. Many cactophiles avoid peat-based potting mixes, but if you're just getting started, a mix of 1:1 mix of cactus soil
erlite should do.
4. Fertilizing: During spring and summer, fertilize once every two waterings with miracle gro (or other fertilizer) at half-strenght. I wouldn't fertilize at other times of the year.
5. *Lithops: Lithops and other mesembs require their own unique cultivation. Watering is the most essential element. Very briefly (many would argue too briefly, but this message is already long), water only when soil is dry and when you see new leaves emerging from the old pair, DO NOT WATER AGAIN (or water very sparingly) UNTIL THE OLD LEAVES ARE COMPLETELY SHRIVELLED AND DRY. This could take months, but if you water too much during this time, the old leaves will perist ("stack") which doesn't look good and can be detrimental to the plant. Mesembs are not for everyone and they can be dissapointing to own if you don't meet their requirements (but most people kill them due to being overly generous with water, etc.).
This should get you going in the right direction. Good luck.