You are basically asking about direction and frequency.
You need a background photon field, and population inversion. Basically spontaneous emission happens in a random direction, and stimulated emission happens in the direction of the background photon field.
The background field creates extra photons, helping the transition from higher energy levels to lower levels
Stimulated emission is the inverse process of absorption, both effect happen at the same time, it is just that because of the background photon field, overproduction happens, and more are emitted in the same direction as absorbed.
Coming back to lasers specifically. It is essential that you have a population inversion. That means you must have a configuration such that the number of electrons Nk around a certain energy Ek is bigger than that of another mode Ni where Ei
You need an optical resonator. This helps the production of a certain frequency of photons.