When choosing terrarium plants, make sure they are small enough to fit in your container, preferably without touching the sides. You'll also want to buy plants that don’t mind a humid environment. This leaves out most succulents and cactus.
However, if you have your heart set on succulents, you can make beautiful terrariums with these plants, but you will want to make a topless terrarium and add clean, course sand to your potting mix.
When considering terrarium plants, look for plants that like low to medium light. I also try to get a mix of sizes, leaf textures and leaf colors.
Here's a list of possible terrarium plants. Lots of others will work, but these are some of my favorites.
Click here for a list of terrarium plants with pictures.
These are great terrarium plants too.