Practical Reality

Let's talk reality.  Have a look at this...
(thanks to http://www.pragmaticmartialarts.com/  for the video)

OK...training in the dojo can never be exactly what we would experience on the street.
For premeditated attacks such as muggings, rapes, and the like, the attacker will usually stack the odds as high as possible in their favor (wouldn't you?).  Nobody likes a fair fight except the victim.  This means:

• choosing places with bad (or no) lighting
• choosing places not visible with security cameras
• choosing unstable terrain such as narrow alleys or hallways, stairs, elevators, etc.
• attacking from a concealed position by ambush
• attacking from the rear or rear side angles rather than the front
• attacking in small groups of two or three assailants per victim
• using weapons
• using surprise or deception to lure victims

Every one of the above lowers your chance of success as a victim.  While sparring can have some place in preparing for the reality of violent assault, what really saves your life in such situations is:

overcoming automatic stress and fear responses
our natural "fight or flight" response is part of our lower brain and evolved to help us survive predation.  Automatic release of adrenaline helps give us the burst of speed/strength we need in such situations.  Sadly, the downside is that this is a short-term benefit which comes at the cost of a loss of fine motor skills and clear, rational thinking.  Mastery of the response can give a lot of benefit by using this energy to help overcome the ambush attack.  For most people, lack of proper training causes this response to become panic and inaction, the classic "deer in the headlights" problem.

physical conditioning
This is simply not an option.  To better your chances of survival you need to be in the best physical condition you can.  While most real fights do not last 15 rounds, the stress can sap your strength very fast indeed.  When your batteries run dry, you are finished.  No matter how good your technique is, poor conditioning means a poor outcome.  I have yet to see any champion fighter step in any ring successfully without good physical conditioning.

muscle memory
You will do what you drill.  Complex drills are good to help break down mental walls and rewire ourselves for the benefit of ambidexterity and to create fluency in our empty hand and weapon techniques.  This, however, must be balanced with constant drilling of very simple techniques so that they become automated responses under stress.  Very important here are the specific movements you drill.  If you drill cutting people's throats with the karambit, this is what will happen under stress, and is frequently used to villify martial artists in courtrooms when they are sued by the survivor's family.  I suggest drilling the footwork heavily, since this makes a huge difference already.  I also suggest drilling defensive responses like elbow cover and head management since these need not be lethal responses.  Low line kicks are another useful muscle memory since they are non-lethal, but can really devastate an attacker when used correctly.  I love weapon drills as much (or more) as anyone, but cannot honestly suggest drilling these into muscle memory.  The risk of using excessive force is just too high.

simple techniques
Complex techniques are fun and challenging.  They help us to get a deeper understanding of spatial awareness, and frankly, it is cool to do them.  Honestly, these are not what will come out under stress.  It will be the simple movements that work and that save you.  As mentioned above, fine motor skills suffer under stress and complex techniques include many variables that will not always work in the heat of the moment.
KISS - keep it short and simple.  Fast, direct, simple technique is what really works.  No, these are not pretty, graceful or elegant.  They are...effective.

awareness of your surroundings
If you review the list at the top, you can quickly see that a lot of benefit can be gained from avoiding those places where ambushes are likely to occur.  When this is not possible, such as getting your car from the parking garage, be on alert that these are high percentage places for attack and act with caution.  Go in groups and be prepared.
It goes without saying that some blame is due to victims who lack common sense and wander dark alleys late at night steaming drunk.  It is wrong to say they are asking for trouble, but not wrong to suggest they are more likely targets of it.

proper use of individual and group pyschology
Luckily, in most attacks, causing injury or death is not the primary objective.
The attacker(s) want your wallet, your pride, or sex.  The violence is a means to an end.
My wallet is not worth dying (or killing) for, and yours should not be either. The schoolyard bully example is an appropriate one in that the bully looks to prey on a weaker opponent, and usually the first bloody nose is enough to get him to seek another weaker victim.  Attackers stack the odds, but also do not want someone to fight back.
Making it clear by your confident body language and posture that you are not a victim can often serve to cause attackers to choose another target.  While I am a strong advocate of ethical self-defense, this is a secondary consideration for me when I am ambushed.  I need to get out alive, and if that means serious harm to the attacker(s) then so be it.  In a group situation this means doing as much damage as fast as possible to the nearest attacker in order to give pause to the others.  I don't expect to always win in such a situation, but I will choose to go out swinging and making sure the winners know they are getting the best fight I can give.

There is no 100% success on the street.  It is at best chaotic and unpredictable and at worst unforgiving and unfair.  Anyone who claims otherwise is a liar (and most likely trying to sell you something).  At best we train to increase our odds of survival, and hope we never have to find out.

That said, good training and a good mindset helps a lot.