Walls and Ceilings - nail or screw to hang on plaster wall

I have to hang a chalkboard in my kitchen that has 80 year old plaster walls covered with fairly new wallpaper. I don't want to take a chance on cracking the wall. The back of the chalkboard has those slits with the bigger holes on both ends of the slit to slide it on a nail or screw. I know how to do it, but can someone tell me if it's less risky to my wall to use screws or nails? And any other helpful advise on how to do it with the least chance of damage to the wall -- like hand screwdriver vs power, drill tiny hole first if I use nails, etc.? Thank you.

It will be less risky to use a screw (no pounding). You'll want the screw to hit the lathe... and you have a 75% chance of hitting the lathe no matter where you try. Maybe you know that there is a small gap between each piece of lathe... so *if* you happen to drill into a spot where the screw does not hold, you got "lucky" and hit the gap. If you move up 5/8" or so and try again, you will be directly into the center of the lathe.

If your plaster is REALLY hard, you might want a small 1/8" masonry bit to punch through the first 3/8" of plaster. But most plaster is pretty soft and a screw will usually go right into it.