Popping out the old races in the rotor and seating the new races fully, is likely the only thing where things can go wrong, unless one has to work in a sandstorm or can't keep things clean in the process.
Getting the new wheel seals properly seated, seated can be a bit challenging too.
Full packing the new bearing cages with grease by hand takes a technique and logic, more than gobs of experience, though I've seen the older mechanic on that one car show with English guys who flip cars get it quite wrong.
If you do it yourself you can remove the dustshields, wirewheel rust treat and paint them.
There likely many you tube videos on the process.