Use a spray bottel of a interior cleaner or dish soap and water in a spray bottel. Spray a section at a time aaaa 1 foot by 1 foot and wipe it clean with a terry towel. This will reduce any drips. You could cover interior with a large sheet or something. Flax soap and a terry towel workes well also or mink oil witch is thick and wont drip at all simply rub and wipe dont know how bad your headliner is-(sometimes on trade ins at dealers lot we use malicos red hot 50%/50%water or stright thinner thow these cars are trade ins and dont belong to any one)and are the worst