As noted above keep it loosely rolled, stored in the bag out of direct sunlight. Keep it away from electric motors and natural gas appliances as both produce ozone.
Opinions vary on what to do with the zipper. Open versus partially closed. Keep it straight with no sharp bends as if you bend the zipper too much you will break it between two teeth and eventually it will leak in that location. Also do not keep it closed as the constant pressure on the "dock" (the last little bit where the zipper seals against the stop) will also cause a leak. The viable options are fully open or closed except for all but about the last 6 inches. I prefer fully open.
Opinions vary on seal saver as well. Most suits use glues that can be attacked by what is in seal saver, so if you use it keep it off the glued seams, where the seal is glued to the suit, etc. On White's dry suits, there is no downside as they use a different system for constructing the suit and no glue is involved in the traditional sense.
Unscented talc also works to protect the seals during storage and absorb anything that might be on the seal that could soften it over time.
Talc works to remove some contaminants while seal saver creates a barrier to protect from those same contaminants, but in either case what is important is to ensure the seals are clean and dry before you store the suit.