I look for sneaky and if there's isn't one try to create a sneaky route, fuck that up and alert everyone then kill all enemies. First time I played Human Revolution I took the tranq gun and went through vents. Came out of the vents and got seen straight away and then had to use a tranq gun with everyone swarming at me. I do the same shit in dishonored too, try to be stealthy, usually fuck it up at first then go on a killing spree. Ironically I love stealth games and I've been playing them for years and have found memories of Splinter Cell and MGS.