I had pressure washed mine before I really stripped it down so much of it was covered already. Mine wasn't really too greasy, it just had a lot of corrosion on it. I spent hours with a die grinder with a wire brush wheel on it hitting everything I could. You can't get into the deepest cracks and crevasses. I taped everything with blue painters tape and it worked really well.
Before paining I washed it all with copious amounts of Eastwoods Paint Prep. I bought a quart of it and used the spray gun to wash it down while brushing it in and rinsing it off. The painter tape held up well even with the cleaner. I plugged the threaded holes with pieces of protection foam (not styrofoam), although that was kind of a waste of time because I chased every hole afterwards with a tap just to clean them up.