I was going to do a post about openings, and the current trend to start with dialog or action before the reader is rooted in the world or has a reason to care about the characters. But, one of my fellow writers at Musa suggested a really good post on openings by Dario Ciriello at: http://dariospeaks.wordpress.com/2012/03/25/openings/ .
His point, that opening with action means engaging the reader, is well taken. Not every novel needs to start with something blowing up. Your "hook" is the question that keeps your reader looking for that next line. "Hooks" can be soft and subtle. Heck, the best ones usually are.
Make sure your reader is asking the right questions, ones that bring her deeper into the story, when she reads your opening. Trust that if there's a compelling question and good writing, the reader will keep going to find the answer.
A point worth mentioning, but that Dario didn't address, is don't use a gimmick. I once read a novel where the main character spends the page thinking about a cock in fairly elaborate detail. Problem? The novel wasn't a romance or erotic. The cock in question was the rooster she was trying to catch and kill for dinner. Can I tell you anything else about that book? No. Why? Because I threw it across the room and yelled at it for about 10 minutes. False hooks annoy me. I think they annoy most readers.
Pose a question to your reader in the opening and deliver an answer in the story. If you do that, your reader will be hooked.