When choosing the right size habitat for a pet snake, you need to consider the species and size of the snake. In general, the enclosure should be at least 1.5 times the length of the snake in both length and width. Additionally, the habitat should have proper ventilation, temperature gradients, hiding spots, and substrate for your snake to thrive. It's essential to research the specific requirements of your snake's species to ensure they have a suitable and comfortable living space.