Focus on one thing at a time – The typical guitar student tends to bounce around, often working on several different scales, a few guitar chords, strumming patterns, picking patterns, perhaps an arpeggio pattern, a little finger picking and then half a dozen songs and riffs all in one practice session. Try focusing on just one isolated skill for a set length of time. For example spend 10 mins just playing the first 2 notes of a scale. Then spend 10 mins on the next 2 notes. See how it feels for a few weeks before you dismiss this approach.
Do strength exercises with appropriate rests in between – One example is to squeeze a note hard so the muscles in your hand and arm fatigue then rest. Repeat until your hand feels sore. Do it just once a week and be careful not to overstrain your muscles. You can also do this by playing difficult chords that require you to stretch your fingers across 5 or even 6 frets while squeezing the notes.
Set a short term goal – Decide for instance that you need to learn a particular guitar solo or guitar song by a certain date. Imagine that you will be performing in front of thousands of people, so you have to get it right. This will motivate you to push yourself and learn the song quickly, and is a good way to practice focusing on completing one thing.
Find a guitar buddy to challenge you – If you know someone who is also learning guitar get together with them and push each other. You can even set a challenges to see who can learn a certain guitar song the fastest or who can practice the most in a week.
Find a guitar teacher – I can confidently say that my fastest progress on guitar always occurred while learning with a guitar teacher. There is something about the influence of a guitar mentor that lifts your guitar playing quickly. It’s like there is a magic transfer of talent.