Building and teaching on the fly can result in an underdeveloped course and an overstressed instructor, a combination that can be deadly for everyone involved. Perhaps the most important quality an online instructor should possess is a generous teaching spirit. An online instructor must truly enjoy working with students. Now, I had some good, if inadvertent, training for teaching online - teaching many years as an adjunct professor. The best online teachers share this same sort of attitude.
More effort is needed.
Even if it's an overload to a regular teaching schedule, you must make time and bring your passion. To create a vibrant learning community you've got to be engaged, not just thinking you'll get your students interacting and check in every once in a while. A lot of online teaching literature suggests instructors get adequate support and training as they create their online courses. However, from my own experience, I'd say that this support might not be effective unless you are willing to make a conscious effort to reexamine how you teach. Most importantly, though, you must simply enjoy interacting with your students.