For the time it takes I usually take thick grease and coat the metal brake lines especially. The local climate takes quite a toll. This is on usually older vehicles I expect to have a long time. I just use a paint brush to apply.

This could be extended to the leveling system metal lines if one expected to have their car for a long time. The grease seems to stay on pretty well and slows oxidation down to almost nothing. It also seems to travel a little or the oil in it does. So even if you do not get perfect coverage it still covers well. Worth the effort in my opinion.