How to efficiently switch between several terminal windows using the keyboard?

In linux almost every terminal support tab, for example in Ubuntu with default terminal you can press:

1. Ctrl + Shift + T or click File / Open Tab

2. and you can switch between them using Alt + $ {tab_number} (*eg. Alt + 1)

also you might want to take a look at terminator

You can use Alt+tilde (tilde = Grave) to switch between windows of the current application. Note that tilde is always the key above tab, it is a tilde in an US english keyboard, but it can be anything in other languages.

If you press the Windows key for a while unity will show you all it's keyboard shortcuts in an overlay:

Finally, near all terminal applications support tabs. The default one in Ubuntu does.

Have you Tried to open multiple terminals using:

Ctrl + Shift + T

Then switching among them using:

Ctrl + PageUP

And

Ctrl + PageDown

I usually use this scenario at least for me