If it's smooth then avoid sanding and use the deglosser, sugar soap is a good start with degreasing but the deglosser kind of etches the surface for the primer.
Sand between coats very lightly. I use a 320 or similar grit soft sanding pad. There are some foam backed sanding pads which come on a roll that are well worth having. They are popular in the auto paint world.
If it's smooth then avoid sanding and use the deglosser, sugar soap is a good start with degreasing but the deglosser kind of etches the surface for the primer.
Sand between coats very lightly. I use a 320 or similar grit soft sanding pad. There are some foam backed sanding pads which come on a roll that are well worth having. They are popular in the auto paint world.