I talk to myself and encourage myself, saying things like "It was a good try!, it was just a try you can keep trying and with each try you get better!, well done! thats the way to advance!, one step at a time, keep going!"
, that way i got over the initial bad feeling of not reaching my goal, it works very well for me, and its very important to me too.
After that i try to see what things i got from that experience, the good and the bad, what new things i learned and what what bad things i should never do again.
But the most important things regarding failures are goals, and what affirmations you have aquired. For example,
i know that getting to a long term goal takes much time, and many tries too, so
I KNOW that failing lots of times is inhebitable, but each try, success or not, is something to learn, if i put some effort on learning from it. Each try is a necesary step, i just need to keep walking, never stop, and focus on the end goal, keeping my motivation up.