I have currently have two hives and have had bees for the last 7-8 years. I suggest you start off with 2 hives. If one gets in trouble, you can always swap in some brood/eggs from the other hive as "reinforcements" or to replace a queen. On average, I lave lost 33% of my hives each year (Read up on varroa mites) It is rewarding but sometimes painful.
I agree with others- try to see if you can join a beekeepers group. There are also some good youtube videos on beekeeping.