Practice doesn't make you perfect

Really.

 I'm not being pessimistic here, I'm being realistic. It doesn't matter if you practice 23 hours a day, you won't be perfect, mistakes are going to happen and there will always be someone better than you, get over it. So here is a tip: grow a pair, don't frustrate yourself.
 As I said practice doesn't make you perfect but is the most important key to success, the only things you need is patience and perseverance, every little step counts. I know practicing can be boring sometimes but in the future you will be proud of yourself, hard work is rewarded.
 This is how I like to practice:

• Make routines.

 Try to practice daily at least a 1/2 hour (1 is recommended), this will develop your muscle memory. I like to take a random "day off", a little break.

• Be dynamic

 Practice at different speeds, different rhythms, different techniques, etc.  A monotone practice is worse than no practice at all.

• Scales are great

  You don't necessarily need to play them note by note, give them some space. Skip some notes, try intervals to make it interesting. 

• Train your techniques

 On your exercises add techniques like vibrato, bending, hammer, etc. You'll kill 2 birds with 1 stone

• Play along to the music you like

 Everybody starts imitating someone, once you earn some skills you can give some of your flavor. For example, I've learned how to play really fast by imitating a few thrash bands.

• Analyze your mistakes

 Find the problem, see what is the problem and fix it, you don't want bad habits interfering.

• Jam

 Use what you have learned to create something new, become a true musician.

 A few last words:
 Remember practice is cumulative, be patient and you will see the results. 
 Use books or the internet to find exercises and warm-ups that fit with your skills.
 Know your limits, don't rush and take it easy.
 Play with feelings, even exercises, don't be a robot.