Mushrooms are almost always the first softies to be introduced, I think if you can get the mushrooms to grow then you have a good chance at success with other soft corals. Another good soft corals is the cabbage coral, the cabbage once established will seek out where it enjoys itself best, in my tank it runs the range from the lower 25% to the upper 10% of the water column. I did notice that a suggestion was Xthenia (sp) they are somewhat funny and do very well in tanks and do poorly in others, I have read that they like a bit more organics then most tanks afford because we have protein skimmers. Finger corals and Toad stools are both good starters as well.
Good luck, soft corals are a fun and interesting way it enter the world of corals. I do hope you enjoy the hobby as you watch them grow and multiple.