Ok, when I play this power chord:

e -
B -
G 2
D 2
A 0
E -

How do I mute the bottom E string? Also, can anyone give me some general muting tips?
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Try wrapping your thumb around the back of the neck and doing it that way, thats how I do it.
Use your right side of your right hand to mute the strings you are not using. Just lean them against the strings.
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you dont have to mute it because you shouldn't be strumming the bottom e string.
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Itll still vibrate a bit if he hits the other strings hard enough so muting is required especially ith distortion or overdrive.
Uhm....is the whole chord muted? Or are you just muting the low E? If you want the whole thing muted, just rest your right palm on the bridge, then slide it just a bit towards the headstock and fret/play the chord as normal, keeping your right palm down. Don't move it too far, otherwise it'll shift the note up.

If you want JUST the bottom E, here's what I do (in general - it can also be applied here.) In general, if I'm doing power chords with the root on the A string, then I use my index to fret the note on the A, my ring finger for the note on D, and pinkie for the note on G. I rest my middle finger on low E (usually in between the frets I'm holding with the others - i.e., if I'm doing a |x355xx| I'll rest my middle finger on the 4th fret) to mute it.

So here, just fret the notes on G and D and leave A open, and rest your middle finger on the first fret on low E.

Hopefully that helps - does for me, I have no idea if it's the technically "correct" way to do it, but it works fine for me.
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