Any advice in life, regardless if personal or business related is about failure.

OK, I know that failure is important in order to get better, but how can I get the most out of it, or even speak of "failing properly"?

Failing is about learning, in childhood this is a sideproduct of playing, later in life, how we learn to deal with failures, relates to "how we decide".
The world could be such a great place if not everyone wanted to be perfect, especially when everyone knows that nobody is perfect.

There is no true or "one-size-fits-all" kind of answer to this never-ending quest, but some habits can lead to make you gain more from a failure.

1. Be prepared
   Preparation is everything, and can only stem from experience. It takes time to get that experience. Determination and persistence lead to a better mindset to decide when is learning time and when not. Get into a training mode and be prepared to fail makes it 50% easier to get a ton more out of it.
2. The right mindset
   Knowing that there is failure is as much important as to know you can´t avoid it. But how you deal with a situation is related to your mindset. If you are prepared or positively know that things happen for a reason and focus more on the reason than on the situation, you are more likely to gain something.
3. Accept everything
   Not as granted but as a lecture. Similar to fear and doubt bears failure a chance. A little fear can turn into excitement, too much fear can lead to depression and loneliness.
4. Use your imagination
   To decide if a project bears failure is not on us, but our experience can teach us, you know when that happens when the red-flags are rising. It rarely happens that we make the same mistake twice, which is a proof that we unconsciously learn from mistakes even without noticing.
5. Learn to see the mistakes of others
   We tend to focus on the success of others to turn our selves down regularly. But if we learn to focus on the mistakes others made, that led to their success is a totally different story and it shows that failure is a big part of the process.
6. Leave the comfort zone regularly
   Taking risks, doing something unexpected or surprise others. This can all bear opportunities to change your life forever. If we leave the comfort zone, we are 120% awake and fully functional, we learn more, and doing this often means, we fail less.