Step 4: Proper watering and maintenance
Plants are needy. Of course, some are needier than others, but the most important thing to know is how frequently to hydrate them. Depending on the plant you get and where you put it, it'll probably need watering a couple times a week. When you water, make sure that you pour thoroughly, so that the water drains out of the bottom. Not enough water could lead to root damage and disease.
If you're curious how the plant's doing, dip your finger knuckle-deep into the soil, and if it's dry you should add water (this doesn't apply to most succulents, though, since they require very minimal water). Also pay attention to the leaves—they can tell you a lot about what's going on under the surface. Wilting of any kind may suggest a watering issue (either too much or too little).
If you're a total flake or out of town all the time you should figure out a way to make sure they don't get too parched, there's a handy paper-towel-in-a-glass-of-water trick.