Any tips on playing electric guitar?

I've been playing guitar for almost 5 years, but mostly acoustic. So
yes, I know a lot of chords and I can pick and strum and what not. I
recently decided that I REALLY REALLY want to get better at electric.
If you have seen, for example, All Time Low live they look like they
strum the power chords, but I know they're only doing the top 3
strings. I would love to be able to do that :3 any tips on not
hitting the other strings and going smoothly from fret to fret and
power chord to power chord? Thank you so much! :D
-Meghan