There has always been some debate as to whether worms are healthy for potted plants or not; this is usually dependent on the plant that is potted and will be different for each species. Worms can be good for potted plants by increasing the aeration of the soil and automatically fertilizing the soil, but they can also eat through the roots of your plant.
Create a mixture of compost and potting soil using more potting soil than compost.
Mix in a few earth worms to the mixture; two or three should be enough.
Fill the pot about one third of the way with the compost and potting soil mixture.
Place the seed for your plant on top of the potting soil and compost mixture.
Add soil and compost on top of the seed until the pot is approximately three quarters full.
Water the plant accordingly and allow enough time for it to grow. The amount of water and time needed for the plant to show growth will depend on the species and the environment it is in.
Add food scraps as a carbon layer to the top of the soil once a month. This will act as food for the earthworms and will distract them from eating the roots of your plant instead.