Scrooge's point is very good advice. If you start with the very easiest things to keep and then work up you will eventually wind up with a tank full of incompatible creatures. It is better to pick the environment or biotope that you wish to develop, or at least the general type of tank you want to have. Then make a list of the inhabitants that fit that environment. Then rank those from easiest to hardest and start with the easiest. For example, if I eventually wanteed to have an sps tank, I would start with a pavona coral, not mushrooms. You generally don't want soft polyps in a sps tank and pavona is by far the easiest sps to keep. Even easier than most LPS is my experience. The same concept will save you money in equipment also. Mushrooms can get by on normal output or lower-wattage power compact lighting. But if you ever want to keep lps, sps or clams then you might waste money on lighting you will eventually need to replace. Same holds for skimmers and other equipment. Even your water movement, pumps and plumbing are dependent on what you want to keep. Unless you want to end up with a communal tank where placement is crucial and every animal is compromised versus their ideal albeit captive environment to some extenet. I think many coral community tanks are the result of polyp-softie-lps-sps progrssion rather than planning and forethought.
