How to improve playing in fast games?

How i can improve in quick games like 1:1? In longer games i dont have any trouble to win but in fast i lost 80% of games. Same happens when i play with my friend, i easy defeat him most of the time, but in fast games i am totally destroyed.

Sry for grammar Englsich is not my native langauge.

     What do you define as a longer game?  15 minutes or more?  

     Doesn't too much blitz chess actually make your chess game worse by making it superficial?

Do a couple big rails and wait 10 minutes before playing. 

The way I improved my 3 0 chess was to play a ton of 1 0 chess! 

Rip your slow chess.

I do ok in slow chess. You will often see elite GMs playing blitz and bullet online hours before their important slow chess matches. Nakamura, MVL, and others can often be found playing on another site just before their OTB games.

The point of blitz is to get a lot of games in quickly. This can help develop comfort with new openings and improve intuitive play. However from my experience your intuition will really only improve playing blitz if you actually make an effort to play good moves. Most of the time I play blitz because I don't feel like thinking too hard and it just results in a bunch of garbage. The important thing is to not get used to moving fast in blitz and then move at the same speed in a long game.

Thanks for answers i define "fast" game as a game of 10/0 or less.

Work on slow games to improve your play overall (which you say you do already), and practice tactics regularly. Blitz games are often determined by quickly seeing tactical combinations, whereas Bullet is all about not hanging yourself while not running out of time.