When teaching guitar, I find that my students need the most help with groove. Students come to me expecting to learn chords, scales, riffs and ultimately entire tunes. I do teach those things, but after a little guidance, anyone can learn them on their own just as well from books, videos, web sites and so on. The harmonic and melodic aspects of guitar take time to master, but it’s just memorization. I devote most of my in-person time with students to rhythm.
Groove is harder to pin down in text and diagrams than chords and scales, so it doesn’t get as much written about it. That gives some folks the mistaken idea that rhythm isn’t as important as melody and harmony. The reverse is true. You can have a long, rich and satisfying guitar-playing life using nothing but the standard fifteen chords, as long as you can groove. If you can’t groove, you can learn all the chords and scales you want, but you won’t sound good.
Here’s an exercise that worked great for me when I was learning, and that I make all my students do. I call it the One Note Groove. It’s pretty simple, you just put on a repetitive beat and play one note over it. Since you don’t have to think about which notes to play, you’re free to devote your entire attention to your timekeeping, your attack, your whole sound — in other words, your groove.