Contrast and juxtaposition makes for a quick and easy to way add tension to any screenwriting element. The contrast immediately raises questions and creates connections for the audience, inviting them into the story. You can apply this tool to any part of your writing.
Character – your character looks one way but talks and behaves another. A brutish lug who speaks like a southern dandy, or a little school girl with the mouth of a sailor. Instantly they create some friction just because they surprise, the contrast in their elements suggesting stories.
Transitions – End one scene with a large image and start the next small, or move from quiet to loud – anything that suddenly changes the dynamic. It forces the audience to question what they’re looking at and why.
Plot – Keep your storylines distinct and different, so when you transition between them it gives the story a little shot of adrenaline.
And so on. Contrast won’t always be the answer to your problems, but it often makes for an effective tool in the writer’s toolbox.