Painting Cloth Headliner. Tips or Suggestions ? ?

I'll give you my $0.02 worth. You certainly can paint your headliner, but it is very different that painting door panels. The headliner is porous, so the paint will have a tendency streak. You will want to spray in light coats with a cross pattern to help eliminate the striping. Plus, you are going to have to mask, mask, mask. The overspray will get EVERYWHERE. I would also suggest taking out the front seat(s). This will give you MUCH improved mobility when moving around spraying the headliner, and I can guarantee you your end result will be better. One more thing. I also always use SEM paint on interior parts. It is good stuff, but as with most spray cans, the spray pattern starts getting a bit splotchy towards the bottom of the can. Add that to the fact that you will be holding the can at a rather steep angle, and you may find that you'll want to switch to a new can even if there is still some paint left. You should consider having an extra can or two so you can switch if the pattern starts to deteriorate. You can always use the paint at the bottom of the cans another time when holding the can upright will improve the spray pattern.
FWIW, installing headliners is not that difficult. I have done several.