You need to watch your terrarium carefully for the first week. This is to make sure it's getting the right amount of light and water. Depending on the plants grouped inside, you will need to decide the placement of the terrarium. A tropical setting will need diffused brightness mimicking the jungles. A cacti or succulent group of plants will need more bright light. Try to simulate the environment they are normally found in. A bright area with indirect sunlight or a well-lit workstation will make an ideal happy terrarium.