Each of these videos demonstrates a very practical route to getting the best rating, which means you will be killing people, albeit within rating-acceptable parameters.

Make sure to leave annotations on, as I use them to explain the nuances of each level and the steps taken to complete them.



Finishing training is recommended, as it gives you a basic idea of how to play the game, something I won't be covering.
The only truly important thing that training doesn't cover is that you need to have a red reticle for a confirmed hit from any given projectile weapon. Aside from that, on expert difficulty the only truly silent form of movement is from the explicit sneak command (default v), which means that taking out enemies isn't quite so lenient as on other difficulties.

Tolerates at least two stuns, and at least 7 or so kills before losing Wolfhound rating.


This isn't an easy level to do without kills in the first place due to a lack of chloroform, so it's relatively lenient in terms of allowing kills. Not sure what the stance is on stuns.

Stronghold allows you to kill the target instead of rescuing them, but in doing so you won't obtain Wolfhound. Make absolutely sure you rescue the target.
Tolerance for kills is around 12 or so, and stuns can be done at least twice.

Tolerance is high so long as you don't kill civilians, though I'm not sure how many kills you're allowed total. Very tolerant towards stuns due to lack of chloroform, you can get away with at least 3.

I'm sure the level is tolerant towards kills (barring civilians as usual), though I'm not certain on stun tolerance.

Guard kills are tolerated, but stuns aren't an option.

At least one stun is tolerated, but no more than around 12 kills.

Quite a few kills are known to be tolerated, though I'm not sure about stuns.

Kills are tolerated in surprisingly large number, but stuns aren't possible.

Embassy doesn't tolerate any stuns, and seems to be okay with a single person seeing you before being knocked out as shown in the video.

On the official Death to Spies website the developers say that the best rating is "playing like sabotuer".[www.death2spies.com]
While this may be considered the best, it's a very slow, tedious and murderous way to play a game that can be done in a more minimalist style, hence the Wolfhound rating.
Wolfhound is as close to "silent assassin" from Hitman, or "Big Boss" from Metal Gear as you can get, with minimal kills and as little noise as possible.

The statistics at the end of a level and objective completion are what effects your rating.

• Combat seems to be generated based on how many enemies die to methods they see coming. Naturally, to get this rating you'll want to avoid that in the first place, but for whatever reason knifing people's faces from the side may sometimes generate a single percentage in this. This won't hurt your rating so long as you keep it under 2% or so.
  
• Aggression is effectively a meter tracking how many people you kill, and what type of people they are.
  Guards tend to be worth half a point in this at any given time, while civilians immediately spike the meter up a good 10% or so on their own, which is often more than enough to mess up a rating.
  All this means is that while killing is okay, it's something you want to avoid doing when unnecessary, and to avoid altogether with regards to civilians.
  
• Noise is simply how many people knew something was amiss. A body being found, or being seen by someone before you kill or knock them out will make this percentage go up.
  The less risk is showcased in any given run, the lower this is going to be.
  Don't be worried about thrown items, whistling, or noise distraction/attraction making this go up. Only gunshots and explosions will raise this rating through acoustics.
  
• Professionalism is where things get weird. Using knives, choke cords and chloroform doesn't seem to hurt this, but using stuns, bullets and explosives does.
  How much professionalism is lowered seems to depend on the level, as some levels are totally fine with you stunning enemies and civilians, while others will lower professionalism by a solid third for even a single stun.
  This is noted where relevant in the guide.
  
• Precision is simply how accurate you are with the guns you presumably never use. Head shots help, body shots don't hurt too much, and missing will hurt it more than a fair bit.
  
• Time doesn't seem to play a role in anything other than the next statistic. Be patient, spend hours in a level if you need to.
  Time is tracked based on overall time spent in a level, so saving and going back is going to be "remembered" by this statistic, amusingly. This is the only thing in the game that emphasizes a no-save, ironman styled single segment approach.
  
• Points seems to be entirely arbitrary with regards to the rating, though I may be wrong about this. No leader boards and no competition in the meta of the game means this is a pretty meaningless number, all in all. That said, if you are just that much of a high-score hound, take note that not using diguises at all seems to multiply your score on some levels.

Based on all of this, the best option is to accomplish all objectives with a minimalist attitude whenever possible in a stealthy manner.
Level based contextual matters are listed above.

Hope all this helps!

I may update this to be text based for people who don't have a solid internet connection in the near future, but for the time being I'm not exactly large on free time.

If you have any questions, any information on level particular ratings system aspects, or anything else that may require action from me don't be afraid to leave a comment, or even add me on Steam.
Hope this was helpful, and if it was do be kind and hit the like button, and don't be afraid to comment. Content creators love to be told how much you appreciate them, or how they can improve.