I think few writers have missed the ever repeated phrase "show, don't tell". However, as a new writer (in fact, even as an old and experienced writer) it's difficult to tell what's showing and what's telling. Some cases might even be more effective "told" than "shown" but that is something to be left until after you can actively make the choice. I'm of the firm belief that rules are meant to be bent, if not broken, but only if you first know the rules.
Back to the vital question: what is telling?
He hated her.
The mere sight of her made him bare his teeth and it was only thirteen years of learning to control his reactions that allowed him to pull the growl back into a pleasant smile.
Which one of these conveys the most images and emotions? I hope you say "showing" or I've failed. But this was easy showing - you're in his head and can convey all these things to the reader without someone else interpretating. When it comes to writing, you must also be able to translate descriptions and characters through a pair of glasses = your POV. That's the active character, the one who sees. If you write with a complete omniscient everyone-included narrative this might not be a problem. However, I can't recall having ever read anything like that. Every story I've read has been from someone's perspective - be it a narrator, one of the 20 active characters or a completely unengaged narrator (a video camera - try Moderato Cantabile by Marguerite Dumas if you want to see how that works).
Now imagine the man in the previous example. He's controlling the flash of emotions, letting nothing show in his opinion because the growl was so brief no one noticed. The active character is now the woman he's meeting and she doesn't have a clue about his emotions. How do I give a sense of hatred from the man?
She could sense that he hated her.
He smiled at her when their hands met briefly, in fact so briefly that he let go before she had barely touched his skin. She felt unbalanced as she straightened, and she tried to understand his hooded gaze and the closed fists he pressed against his sides.
Granted, my showing isn't all too clear that he HATES her. He might be embarrassed, scared or just feeling awkward. But it gives enough away for the reader to pick up other hints along the way that might explain it more clearly. Also, is it important to know his exact feeling? The tension is there, the promise of conflicts and perhaps danger. That might be all you need.
The most difficult part of "showing not telling" is to describe when your own active character (POV) isn't aware of what you want to describe. We deny our own emotions, we doubt what we see and what we sense - we do this in real life and it should happen in writing as well. Even if you write fantasy, people are people. Alright, I give you the benefit of a doubt. You might decide to do a superadvance sci-fi world where people are completely aware of themselves. You can now go write something fantastic instead of reading the last paragraph (or go buy chocolate, make tea, watch Firefly).
She didn't realise she loved him.
Her chest tightened as he kept avoiding her eyes. Annoyance filled her and she brushed hair away from her face, molding it back into the curls falling down her back. He was being silly; it had been a long time since high school. Just because he had changed into some dropdead gorgeous brat he didn't need to stick up his nose like this. She had known him when he was a fumbling fifteen year old and she remembered he hadn't always had money on the bank or a face fit for ads. All he had had back then was his smarts, and she had longed for the ease with which he passed every exam thrown in front of him. It was unfair, she thought as she studied the indifferent expression on his face as he began talking to her husband. He had it all. She sighed, but she couldn't even envy him for it. She looked to her husband, then to the young upstart again. They were a world apart.
I think you all noticed the difference in length between the paragraphs. Showing takes more space, especially when you're showing something of which the active character isn't aware. I even compressed this more than I would have liked. To reveal things hidden within like this often takes a full manuscript , just consider the romances you have watched. I'm not saying romances are the only genre with it, but they are the stories where these hidden emotions are vital for the plot.
I have focused this post on showing emotions, but it's possibly to apply the same strategy of replacing an adjective with verbs for other descriptions.
It was a warm day.
The breeze licked her face like a human breath, and she stretched her naked legs out into the sunshine, hoping to make her dark skin shine golden by the end of the summer.
I now wish you good luck with your writing. You got more examples of "showing not telling"? Post them in the comment section, I'd love to read and discuss it!