Start out with some basic orange montipora cap. It is cheap and hardy.
If that does well you can try some millipora
Then after several months of success try some easier acros like staghorn or green slimer.
Don't buy wild colonies. Buy aquacultured (not maricultured). The wild colonies are more likely to carry disease/pests and have a hard time acclimating from the ocean to the tank. Also do some research on dipping your sps corals. There are a lot of pests and disease associated with SPS. I learned the hard way