Guitar picking can be bit tricky but let’s discuss how to make it an easy and fun ride, let talk about thumb strumming and picking for the sake of this brief abstract.
So playing with thumb is an amazing experience, you can do a lot of crazy stuff with just one finger, for eg jeff beck is one the greatest guitarist of the rock it hard era and if you see his live concerts you will be able to observe how beautifully he uses his thumb to create pitch bends, tone change and add amazing harmonics, with just one finger he can create magic , so it is evident that playing the whole set with a thumb is totally possible, as i was taking about jeff beck playing with a thumb and adjusting the tremolo bar with his hands for pitch shifting , makes it quite evident that it is possible to pull off full set with one thumb.
As we all know thumb is one of the strongest finger we have hence it has the muscle strength to generate the right amount of hit , but on the other side with great power comes great inertia, the thumb is powerful but lack flexibility and the right shape, so in order to play amazingly with a thumb you gotta have a strong muscle memory that can provide you the right amount of strength and flexibility to execute arpeggios and chord progression smoothly.
If you are going to play swing and bossa-nova or let’s say neo classical stuff then you will have to get the thumb arc like a half moon and get thumb and the palm joint to be swift and flexible, small muscle moments with the right velocity and pressure is the key.
Develop strong Finger and palm muscles control and try to develop the right momentum , as soon as you integrated wrist rotation with the strumming fingers it is a smooth ride after that .
If you are finger picking in indie, blues , bosa nova etc the thumb usually handles the bass strings or let’s say the bass side of the composition and the other 3 fingers will handle the treble side of the composition or strings with higher pitch ; so if you are finger style player then you will be able to balance both bass melody and the treble melody in a real good way.
Easy way to master Thumb strumming is to practice this small exercise , let’s start ; try to keep the fingers away and rest all your fingers on the sound board and strum across all strings and pick all 6 strings one by one with your thumb, develop six string thumb independence and you will see just with the help of your thumb you can create beautiful rhythmic melodies.
Access both treble and bass parts with thumb as it adds more dimensions to your thumb playing and give more freedom and these above mentioned methods will improve your pick and thumb strumming to a very high extent and will add lot of dexterity to your playing.