TL/DW = the unknown.
- Limit the point of view so the reader has limited information.
- Choose the right setting to limit the known.
- Style and form can be used to mess with the conveying and pacing of information.
- Dramatic irony can be used to reveal some information to the reader that the characters don’t know.
- Cliffhangers can be used… If you also like coming up with implausible resolutions to them.
See also: http://www.writersdigest.com/qp7-migration-conferencesevents/nine-tricks-to-writing-suspense-fiction