I have to ask, do you have these things Enabled or Disabled. If not I think you should try, and this wont do any harm to your device. Just avoid disabling anything else. Don't make the Noob mistakes I made in the past.
Currents
This is always running in the background, I've found just Disabling this can make a huge difference
Google Play Services
This one is like the Centre piece for Youtube and Hangouts, probably some other things too, but I don't use them. And it will only ask you to enable it, if disabled when you start the other apps.
Google Play Store
I've often found this to be a pain, I only go on there to search for an App or Game, some times I skip it and try other places. Because you use it once and it stays there for a while.
Google+
I am not entirely sure what this one does, but it hasn't bothered me since I disabled it. So I guess I don't use whatever it does.
With only these 4 (annoyances) Disabled, I've managed to make my N7 last very closely to 2 days. That's 48 hours of enjoyment.
Oh and I did this on 4.3, it works just as well for 4.2.2, but I can't say much more, never got around to trying the previous versions.