Like everything else in this business, you never really finish learning to critique. You just widen the repertoire: my earliest crits were horribly lame (yes, to those of you who've 'enjoyed' a Kate-shredomatic critique, I had no idea at first).
First things first: never, ever crit with "This sucks" or worse, "You suck". It's insulting, and worse, it doesn't do anything to tell the author what they need to fix. The whole point here is to improve the story. If you absolutely loathe the concept, it's okay to bow out with a comment to the effect that you wouldn't be able to give the piece a fair critique. On the other hand, "It's wonderful!" is equally useless. If you really can't see anything that needs improvement, look at what worked really well in the piece and comment on how effective it was.
Next, for those on the receiving end: remember that the goal is to improve your story. Not everyone can manage to be tactful - I've been told that even my gentle critiques are pretty rough on the recipient, not because I'm nasty, but because I've learned to be thorough. Of course, I'm the woman whose idea of 'tact' is "Nail stuck through it to fasten it to the wall", and who's about as subtle as the blunt end of an axe. A good critique can hurt, especially if all you've had is how wonderful the piece is. If it does hurt, do not respond immediately. Wait a day or two, until you can look at it without getting steamed up, and then evaluate the critique against what you've written. Chances are you'll find that there's a problem you need to fix.
The third general piece of advice is this: try to say why you think something is a problem, and if you can offer alternatives, do so. If you can't, that's fine - the idea is to try to hit on the reason something doesn't work, and possibly get the author thinking about how to make it work. Even knowing something doesn't work and why is often enough.
Finally: Do not, under any circumstances, do everything that your critique group says you need to do. Evaluate the suggestions, look for common issues - if everyone has a problem with scene X, then chances are there's a problem - but it may not be the problem that was identified. It could be that the problem is quite different and everyone hit different symptoms. Also, it's quite common for a critiquer to have a different vision for a piece than yours, which means that their critiques are going to be somewhat off-base. This is particularly common when you're critiquing a novel chapter by chapter, or scene by scene.
Okay. With all of that out of the way, your mission, should you choose to accept it, is to critique the scene below. I'll be commenting on the crits and suggesting better ways to make your point. Oh, and in case you're wondering, this is raw unedited draft (which I don't usually inflict on people) so there are plenty of issues with it. It's also the opening of the new thing.
// Start snippet //
Dowager's Square swarmed with activity in the perpetual half-light of the Great Eclipse. William Seraph, Lord Alvar, emerged from his dark stone townhouse, smoothing his gloves as he paused on the top step to survey the scene before him.// End snippet //
Across the square, the turreted silhouette of the Imperial Academy of Engineers appeared black against the dark outline of the sun: a fairytale castle outlined by a shadowed sun that occupied fully half the southern sky in perpetual midday.
Though Dowager's Square was a prestigious address, street vendors crowded the huge space, all calling their wares in such cacophony that Alvar often wondered how anyone with a front bedroom could sleep. The Academy students were frequent customers, seeking variety in diet - and, alas, other matters - when they had time to spare.
The comforting burr of countless mechanisms surrounded him, their tingling warmth as familiar to Alvar as his own body. Years of training at the Academy had honed his natural gift to a level where Alvar could distinguish the different kinds of mechanisms and even identify individual devices with which he was familiar. Unlike many of his royal cousins, Alvar's right to the title of Engineer was fully earned, no honorarium in recognition of their ancestry.
Something was wrong.
The faintest hint of a frown touched Alvar's brow as he strode forward. People parted for him, perhaps sensing his presence. He could sense nothing wrong in the 'canics around him, yet uneasiness persisted, a nagging suggestion that evaded his conscious awareness.
Heat rose through the soles of his boots, the heat of molten rock so close to the surface it might break through at any moment, but for the combination of a multitude of steam driven devices to draw off rising pressure and the immense multi-layered motion dampers with their springs thicker than a man's height. All seemed well to his senses.
Every step on the paved square heightened Alvar's disquiet, driving him to probe to the deepest extent of his gift. The first hints of rust in a household radiator to his left tasted faintly sour, and a poorly oiled flywheel in the student quarters of the Academy buzzed off-key. If Alvar recalled correctly, that was one of the devices used to test precisely how sensitive a prospective student's gift might be. Students unable to diagnose the problem were relegated to Mechanics, capable of building and repairing to specifications, but not sensitive enough for true Engineering.
The multi-layered alloys of the dampers beneath his feet jiggled as the springs adjusted to shifting lava beneath them, strengthening the thin crust of the busy square. The movements were too small to be detected by ordinary senses, so small that one could stand a penny edge-on and it would not tip - though here the likelihood that a penny would remain unclaimed more than a few heartbeats was small indeed.
The respectable stall-holders competed with whores and beggars, the Empire's waste chasing any means by which they might sustain themselves - or drown themselves in forgetfulness for a little longer. Though constables chased them from the square once the Palace bells tolled curfew, they returned with the waking bells, and remained through the day, using the crowded square to avoid any constabulary attention.
Alvar had no doubt those unfortunates lived a life far grimmer than anything he could imagine. Their stunted bodies and gaunt faces told their own stories.
Someone emerged from the crowd, running too quickly to stop. In the moment before they collided, Alvar glimpsed ragged gray clothing flapping from a skinny figure. Then he fought to both stay on his feet and hold his assailant. It was a common trick: bowl over an unsuspecting nobleman, then ones colleagues relieved the gentleman of his valuables while the one responsible for the collision helped the victim to his feet and apologized profusely.
"Please, milord, yer an Engineer, ain't ya? Tell 'em to get away from 'ere! One o' them big springs is gonna go."
The desperate tone and the blazing strength of the boy's gift froze Alvar in place for a long moment. How had the Academy talent scouts missed him? Then the import of the boy's words sank in. "Where?"
The boy pointed to the ground almost directly beneath Alvar's feet.
He sent his gift that way, probing the spring. The sense of unease, the nagging certainty of something wrong, intensified.
Alvar followed the nausea, probing where it strengthened.
Another Engineer's presence beside his, strong but untutored, guiding him unerringly to a point on the spring where Alvar initially saw nothing wrong, nothing but his own gift's insistence that something was not right. He probed deeper, seeking the finer structure of the tempered alloy.
Ice flooded his stomach and he swallowed in a mouth gone dry. Metal fatigue: the one thing all Engineers dreaded. It was so cursed difficult to detect, and so lethal in its results. A fatigued part could go from apparently perfect condition to catastrophic failure in a heartbeat.
"I have it." He pursed his lips and gave the Empire-wide signal for impending disaster: three short whistles, three longer, then three short. The piercing tone cut through the din, bringing Alvar the attention of many of those present.
He raised his free hand above his head, signaling the crowd to move themselves away from where he stood, and marking out the expected direction of failure. Every child learned those signals, and knew to obey without question.
Frightened babble rose from the hush, and people rushed away, shopkeepers abandoning carts and pushing at those too far to have seen the signals. As always, fear generated its own momentum, infecting those beyond reach of Alvar's signals to send them fleeing with those who knew what approached.
The boy tackled him, knocking him off balance and sending them both skidding along heated paving stones.
A sharp crack of stone and metal breaking shattered any reproach Alvar might have considered. The sound seemed to echo without end, though as he hauled himself to his feet, one small part of his mind calculating the cost of a ruined suit, the sound modulated to a steady hiss of escaping steam.
The boy had saved his life. The newly opened gap was close to six feet in width, and already the edges were sagging. It would have swallowed him, if the escaping steam had not scalded him beyond healing.
Alvar caught the boy's shoulder. "Come. You should be in the Academy." Already the Academy's bells were signaling a breach in Dowager's Square and a summons to all Engineers to assist with repairs.
To his credit, the boy made no attempt to free himself from Alvar's grip. That was not reason enough for Alvar to trust him not to flee. The youngster's ragged clothing and dirt-crusted skin was clear evidence he was from the lowest classes, and could be expected to fear authority. Undoubtedly he had committed any number of crimes merely to stay alive: a reason the courts rarely gave any credence. If arrested, the best the lad could hope for was exile or virtual slave labor at one of the outer colonies. There were worse fates.
Critique away - I'll be responding with commentary, and if you're really good, you may even get to see the final result. Eventually. Possibly a very long time from now, since I usually hammer through the first draft from beginning to end, then go back to clean up - but I do take notes.