A Tremelo is a rapid alternating motion [Think of Russian music or spy music]. Tremelo picking comes from a RELAXED wrist and NOT the forearm, elbow or shoulder.
Count 1 & 2 & 3 & 4 & and let your “Wrist” lightly pick down and up on one note. You can then gradually build a rapid alternating speed. Also try “Accenting” the first note in each bar. [Always avoiding tension in the elbow].
1 STRING TREMOLO PICKING
Now play it by “Doubling” the speed and INTERNALISE [Feel] the “1e & a” Rhythm. Count it in your mind as you start with a down stroke and pluck down up, down up, down up etc .
CROSSING 2 STRINGS WITH GUITAR TREMOLO PICKING: “EVEN GROUPINGS”
First try this with 8th notes and then double the speed with 16th notes. Hear the internalised “1e and a” of the Sixteenth notes and as you tremolo pick across the strings you will always cross with the same “EVEN” stroke. This makes crossing the strings very easy because when you can cross 2 strings then you can SIMPLY REPLICATE this across all 6 strings.
EX.4 TREMOLO PICKING SCALE ACROSS ALL 6 GUITAR STRINGS:
Just replicate exercise 3 with a scale this time ascending and descending across all 6 guitar strings starting with a down stroke creating “even” tremolo picking. [It will be smooth and musical and simple with even patterns].