I spent some time researching plaster for my bathroom remodel. Because of the different types, since my house is wood frame, I should use Lime Putty, which is an aged version of hydrated lime (lime cooked in a kiln at over 2300c). The hydrated lime needs to be aged by sitting in water for at least three months. The Romans aged it for at least 3 years. This stuff gets stronger by absorbing carbon from the air as it cracks, so self repairs.
The reason for lime putty instead of some pre-made mortar mix, is because the mixes all have concrete mixed in which would trap moisture and rot the wood.
As for the technique, the plaster should be applied in three layers. The first layer would be made of the purest mix and scratched to form ridges for the next layer to grab onto. The second layer would have more somewhat coarse sand and fibers like hair or fiberglass. the third later is diluted even more with the finest sand so it gives the smoothest finish.
Haven't actually done this yet, so going by memory. Finding hydrated lime at a hardware store is really hard, may have to go directly to the producers (one in a nearby state), then soak it in 5 gal buckets and wait.