The answer, according to most advice on writing, is to have 'conflict', but conflict is not a particularly helpful word, it's both general and limiting; it's not specific and in fact refers to only one scene-making technique available to writers. Drama – by which I mean compelling story events – can certainly grow out of conflict, but it can also grow out of difference, disparity and contradiction.
The one thing that all of these terms have in common is that they rely on the existence of two states. Conflict is one way to create drama from them, but a character desiring to move from one state to another is also a potentially potent form of drama – from pauper to prince, from slavery to freedom for example. Further drama can also be drawn out by complicating the relationship between the two.
The key is, it's not the states that are interesting but what happens between them. It's the space in between - the gap between the two - where drama will grow.
Here are six relationships that can be used to create drama in your scenes without every one having to be a combat-zone.
Between expectation and reality
Imagine a man making breakfast. He turns the gas-hob on and clicks the ignition button – it doesn't work. We have a gap between his expected response from the world and the actuality - a mini-drama. He goes to turn the hob off but the knob comes off in his hand - another gap between expectation and reality. He goes to the door to open it but its jammed shut – increased drama. He opens the window but the fire-escape has been ripped from the wall.
You get the picture.
Between desire and satisfaction
Any romance writer will tell you that the key to creating compelling narrative is to keep the ideal lovers apart for as long as possible. But it doesn't just have to be love – any delay between desire and fulfilment creates drama. What's particularly useful about this technique is that it also creates narrative propulsion.
Between desire and duty
A further complication of the previous drama – the protagonist wants something so very badly but duty denies it her. Betrothed to one person but you fancy someone else? The law preventing justice? Politely enduring the pointless inanities of a relative while the girl of your dreams slips out of your life?
Jane Austen was so very adept at this. Intensely powerful dramas without a fistfight in sight.
Between the actual and the possible
This vignette covers a whole raft of dramatic possibilities. It is dramatic because it allows for a transition, for a difference to be made, a hero's journey. The shift does not have to be a good one – it can be dark and tragic. Macbeth is driven by what he and his lady believe is possible. It's the difference and their knowledge of it that drives this drama.
There is all sorts of fun to be had here – whole acts can be written about just getting a protagonist to appreciate what is possible before he even goes about trying to make it a reality. To use granddaddy Shakespeare again, the witches serve this purpose in Macbeth.
It's also more interesting when the protagonists, while striving for a particular possibility, end up somewhere else entirely.
Between truth and its impact
The truth is always good, right? The truth will always set you free? Well, maybe - but a whole heap of pain and suffering may have to accrue along the way. Drama always ensues when the truthful choice is loaded with potential collateral. So you see your friend's wife with another man – you going to tell him if you know he's going to leave and the kids don't get to see their daddy so much? You know the janitor at work has a criminal record - you going to tell the boss when you know he has six kids to feed? It's called drama, my friends.
Between character and circumstance
A worthy source of drama used by storytellers as diverse as Stephen King and Anton Chekhov. A character thrown out of their comfort zone and placed in challenging situation can be the basis of an entire novel – a device frequently used by King. Chekhov's technique exploits the same relationship but in a much different way – his characters are stifled and disempowered by their circumstance, and he mines this rich vein of dramatic potential.
So, when faced with a flat scene, don't immediately resort to a man walking in with a gun – consider the two states that are at play and your characters relationship to those states, and the scene will write itself.
And if the scene still stinks, it maybe that you're missing these elements and it's not a scene worth writing anyway.