In fact, this article is written on a bluetooth keyboard (Rapoo E6300 which I received on Christmas).
The keyboard is charged via USB. After turning it on, the Android phone has to activate Bluetooth and pair with the keyboard. Therefore I reach the Bluetooth menu via the Quick Access (drawn from top) by hitting the triangle pointing downwards. After initial selecting the keyboard, the displayed passcode has to be entered and submitted on the keyboard.
Bear in mind, that BlueTooth has its own can of vulnerabilities, though. So think about when you want to activate it.
In the settings on Android there is an item about input and language. You can find a new entry about Physical Keyboad there listing your keyboard. Picking it allows you to select your keyboard layout. Note the hint, that you can switch between the layouts with Ctrl+Space.
The only drawback I noticed so far is the missing AltGr key. Therefore I switch from my German layout to US International and back. This way I can enter
@ if needed.
To prevent damages on the keyboard, I bought a case the other day.
Happy blogging :-)