Fall is the easiest time to plant, as watering requirements diminish as the weather cools. That being said, you can plant a container plant at any point of the year, so long as the ground is not frozen.
“When in doubt, let it dry out!” The number one killer of houseplants is too much water. Water less often in the winter. With fewer hours of daylight and lower temperatures, plants will dry out less often. To know for sure, purchase a moisture meter.
You want to dig a hole that is twice as wide as the pot that the plant is coming out of, but no deeper. It is important that the root flair, the point at which the roots come off the main trunk, be planted at the natural grade.