Principles of Rhythm Guitar
Firstly your right arm should ALWAYS BE IN MOTION.
and up strokes on the "up" beats (or "off" beats) by
which I mean
This keeps you in time WHETHER OR NOT you are actually hitting the sttings. So many rhythm guitarists make the mistake of only hitting the strings when it's "needed", this gives a choppy sound (instead of fluidly organic groove).
It also permits "follow through" (much the same concept as playing tennis or golf - you don't just hit the ball and STOP - you continue moving "through").
As an exercise to this end, begin by only hitting the
strings with downstrokes on beat 1 and beat 4. (Even though your arm
is still in constant down/up/down/up/down/up/down/up 1 + 2 + 3 + 4 +
motion). It doesn't matter which chord you choose to play.
Next, hit the strings on beat 1 (downstroke), beat 4
(downstroke) and the "and of the 4" (upstroke).
Once you're completely comfotable with that rhythm,
hit the strings on beat 1 (downstroke), the "and of the 3 (upstroke),
beat 4 (downstroke) and the "and of the 4" (upstroke).
Note that in the above examples, each is virtually the same, except that the region of beat 4 gets a little busier each time.
A downstroke on beat 3 is entirely predictable (and pretty boring). Hitting beat 3 is ok if you're playing a March or a Polka, but with most "modern" or funk based musics a "pushed 3" is preferable.
The "pushed 3" is an upstroke on the "and of the 2". This adds rhythmic tension and makes it much more exciting.
Note that in all the above exercises, we are avoiding beat 3 like the plague, and that the principles of "spare and ringy at the beginning of the bar" and "busier towards the end of the bar" remain intact.
"Exercise 4" is like "Exercise 3" above but we are simply adding a downstroke on beat 2 into the mix.
This has been called the "Universal Rhythm" by some.
The general rule of thumb is
The best rhythm guitarists have impeccable taste and
totally subscribe to the notion that
On a final note, many rhythm patterns are two or four bars long (as opposed to the patterns I listed above - which are only one-bar patterns), and in many funky and latin musics you will also find a "pushed 1" (accenting the "and of the four" with an upstroke to replace the "expected" downstroke on beat 1).