First Timer: Quick Disconnect Question

So this is really a stupid question, I just don't want to mess something up.

I finally have some beer ready to put in a keg. I'm going to force carb.

Any special order on how I connect/apply gas, etc.

For instance should I have the gas shut off. Pop on the gas disconnect, pop on the "beer out" line and then turn on the gas? Does any of this matter?

Reason I ask is that I've read about people getting beer in their regulators, etc but I don't know how this happens.

What mistakes could I possibly make?

If you absolutely want to make sure not to ever get beer in you regulator or gas lines, then:
-Install a check valve on every gas line to keg
-Bleed pressure on keg before attaching gas disconnect
-Never fill keg all the way to the gas post diptube