If you dont have any live rock (LR) now is a good time to add it, as you wont need to worry about curing it. The LR will help cycle your tank and provide a surface for beneficial bacteria to grow on. If you're not planning on adding rock, throw a cocktail shrimp or two in your tank. This will kick start your ammonia spike. You can always do both aswell. If you dont do either of these, that one hermit crab wont create enough waste to cause a significant ammonia spike, which in turn wont leave you with enough beneficial bacteria to support a large enough bio load, if any at all. Those Damsels you read about can also be used to cycle your tank, as they are a very hardy fish. I would reccomend the shrimp though. Remember to plan ahead, take your time and do your research! There are loads of threads with valuble information on these boards. Good luck!