Mint plants have a fast-growing root system, which is why it's best to plant your mint in a pot. If you plant mint in your garden without a container, it will quickly spread to take over the entire garden.  If you want to plant your mint outside, dig a hole at least 5 inches deep, and place a container (such as a pot or a mesh bag) into the hole. Then, plant your mint inside of the container and pack dirt on top of it. The container will keep the roots from spreading to the entire garden. If you want to plant your mint indoors, purchase a pot to plant your mint in. Place the pot near a window where it will get sunlight throughout the day. Don't place the plant near a heat source. If you're leaving your mint outdoors, when you plant your mint is important. Make sure to plant your mint in the spring if you live in a climate that experiences winter. If you live in a frost free climate, mint will thrive in mid-fall. Make sure to water your mint often, as mint thrives in damp soil. Mint can grow in a variety of soils, but doesn't do well in dry environments. If you live in a dry environment, keep an eye on the plant and water it more frequently. Water your mint plant at least once per day. For the most part, mint should grow well enough on its own. However, you should occasionally supply a light amount of fertilizer to the soil surrounding your mint. This will encourage healthy growth. This can be especially helpful if you harvest your mint a lot.  Do not fertilize your mint often. Harvesting it every 3 to 4 weeks should be enough. Choose a fertilizer that's low in salt, as salt can cause the tips of mint leaves to turn brown. When you plant your mint, plant it so that it is about 1/4 inch below the surface. You should only plant one seedling if you're using a pot. If you're planting your mint in your garden, plant each seedling about 2 feet apart. Be sure to plant each seedling it it's own container.  Make sure to plant mint where it can receive sunlight. When planting mint in pots, make sure you can move the pots near direct sunlight. Do not choose pots that are too big to fit on a porch or patio. While it's best to grow mint outdoors, you can plant it inside. If you choose to do so, pick an area where your mint will be consistently exposed to morning light. You should also keep it away from anything like a heater or furnace, as this can dry mint out. Make sure the pot you use to plant mint is free from cracks. Mint roots grow fast, and they will spread through the crack of a damaged pot.

Summary:
Plant your mint in a pot. Choose the right time to plant mint. Water your mint plant often. Fertilize your mint on occasion. Plant your mint properly.