Lots of good advice so far. Here's my own contribution...

1) Try to think of a unique angle to your story. Just because someone ends up tied to a bed, doesn't me it can't be interesting to read about how s/he got that way. No matter what people say, every story HASN'T been told before. Believe that you have something new to offer. Toy with the idea in your mind and when you feel something formed (particularly the beginning AND the end, sit down and write it. The middle stuff is easier when you have the start and end already formed in your mind.

2) When it comes to the 'hot' part of your story, don't hold back, don't be afraid to give the dirty details. Go for it. Deliver!