Tips for controlling tension?
Basically, don't give your character what they want. If you character's has a goal, don't let them achieve too soon or put a couple of caveats on it that they have to figure out how to resolve or work around.
Don't reveal too soon and on the same note, don't purposely keep context information from the reader to create an air of mystery thus creating tension. I mean there is a right and wrong way to create an air of mystery. You want readers to ask the right questions and not the ones where they are clearly confused and don't understand what's going on.
Don't bog the story down with things like to explain backstory in one huge info-dump or a flashback. Sprinkle in character backstory through the progression of the story. Well, relevant backstory bits. I'm a firm believer in that my character's backstory shouldn't take precedence over my actual story.
Don't introduce a subplot you aren't going to finish just for the sake of creating tension. I just don't do this because it annoys the crap out of me.
And that's about all I can think of.