Not much, except to ensure that the bucket & loader is dead flat & limp on the ground with absolutely no pressure in the lines (wiggle the joysticks in all direction with the engine off) it will be messy so have some absorbent pads, rags, etc.
I just replaced some FEL lines on my tractor. The air line in the lines will take care of itself during the first operation. I just replaced 1 line at a time, so I did not get the lines mixed up.
Make sure the new lines are clean internally. Don't presume because they are new there is nothing in there. A burr of rubber can cause havoc on your pump.