1. Know Your Current Skill LevelPracticing correctly involves proper knowledge of your current playing skill and what you hope to achieve with a certain exercise or practice session. You cannot play exercises designed for advanced players in a beginner stage or if you're an advanced player, playing an exercise made for a beginner might be a waste of time. Selecting exercises best suited to your playing skills is very important, and so is setting a realistic goal on what you hope to accomplish from a particular exercise.
2. Set Realistic GoalsSet a proper goal on what you hope to achieve from a certain exercise. I mean, you can't become a guitar god by playing an exercise you find effortless at a slow tempo. You ought to know how much improvement there will be from a certain exercise or practice session. This will prevent disappointment caused by setting unimaginable goals.
3. Practice With Full FocusThe most common reason for finding guitar practice boring or ineffective is when you practice without focus and concentration. If you practice while watching TV, then change your ways immediately. Guitar practice is something that is to be done seriously, with one's full attention and concentration. Otherwise, you'll just be another weak guitarist who dreams of becoming a better player but does nothing to do so. Just make sure that whenever you practice, you do it with full vigor.
4. Challenge YourselfIf you can play a particular exercise too easily and without much effort at a certain tempo, then you're not doing yourself any good. An exercise will only be useful, if it requires a certain degree of effort to play properly. Of course you don't have to play an exercise that is too difficult for your level, but you also can't play something that's too easy for you. Whenever you can perform an exercise at a reasonable level of ease, just increase the difficulty. Progressing as a guitarist is only possible if you constantly raise your level.
5. Don't Rush Into ThingsDon't rush into playing at higher BPMs or playing difficult exercises before mastering an easy one first. I've made this particular mistake and if you do the same, you'll just sound sloppy and will be disappointed by your playing. Ensure that you sound fluid and clean before moving on to faster tempos and tougher exercises. Patience is the key here. Moreover, don't compare yourself to other guitarists. Everyone learns at different speeds. In order to get the best from practice, ensure that you are comfortable by your learning pace.
6. Always Practice With a MetronomeMake sure that you always practice with a metronome. It helps to establish a proper sense of rhythm and timing. Plus it's important to maintain the right tempo when playing a difficult exercise. Your playing must be consistent; otherwise, you'll just end up sounding sloppy. And yes, exercises do seem boring when played without a metronome.
7. Playing Songs is Not PracticingYou'll have to understand this one properly. Playing songs is not practicing. Practicing does not include covering or playing songs. Playing songs when you are meant to be practice will only waste your time. You ought to have different time periods for practicing and playing the guitar. Understanding this difference will only do good.
8. Spend More Time Playing Exercises Rather Than Searching for ThemThe internet offers a vast resource of exercises which can be easily looked up. But the problem is that many people follow an incorrect method of practicing and then, they blame the exercises. As a result, instead of improving their method and practicing, they look for more exercises, which ironically, they won't use properly either. So, focus more on practicing and playing exercises, rather than searching and searching for the so-called perfect exercise. You'll never find the perfect exercise, you'll just have to step up your game accordingly.
9. Practice DailyAlways practice the guitar daily, even if someday you're busy and can only play for a short time. Practicing 10 or 15 minutes every day is better than practicing 60 minutes once a week. Try to follow a proper practicing schedule, and don't break that schedule.
Finally, I'd like to say, don't give up practicing just because you don't get the desired results. You just have to correct your method of practicing.