Added another 200 words to my thief scene. Here's what I got so far:

The thief moved his foot, which made the leaves of the bush rustle a little. He had not prepared for this, but the guard stood so close that he had to do it. While the plant made a noise like you would expect it to sound if a gust touched it, he let the slide push the first bullet into the chamber of his silenced gun. He had studied the piece inside and out, so he knew that no matter how hard you tried, it would always make this little clicking noise. Fortunately the rustling was loud enough to drown the click. While he performed this stunt, the thieves gaze was fixed on the guard, who didn't give any indication that he even noticed something unusual. His black clothes made it possible for the thief to be invisible among the leaves. Without a sound he moved around so he could point his gun at the lamp above the guards head. He bent his knees, ready to jump, aimed and pulled the trigger. His surroundings went black instantly, which was a good thing, since in the same moment he leapt out of the bush and onto the guards back. Covering the tall mans mouth and nose, he put all his strength into silencing him, while the man started to turn around, reaching for him with his shovel-like hands. He had strong arms and fingers and sealed the guards respiratory tracts airtight. Predicting his movements like he had done it with so many others, the thief easily dodged the paws that clutched at him. "Let's hope he doesn't do what he… damn!" the thief thought as the huge man jumped backwards, aiming to crush his assailant between his body and the stone floor. "I'll have to hurt him." he thought.He had to react fast, so in one flowing motion he pulled himself up the giants back and stepped on his shoulders, as both bodies moved towards the floor fast. An instant before they reached the floor, the thief removed his hands from the face. Following a reflex, the guard took a breath - at least he tried to. They came down hard and whatever air had been left in his lungs was pressed out of them by his own weight. The thief immediately covered nose and mouth again, spun around so he was squatting on his chest and drove his knees painfully into the guards shoulders, breaking both his collarbones. He could see the pain in his eyes, but not for long, since the big man finally fainted.