1. Selecting topical medications based on the nature and stage of the lesion: This is the primary consideration in treating skin diseases with topical medications. For the same skin condition, different stages (progressive, stable, regressive) and different natures (acute, subacute, chronic) will significantly affect the choice of medication. For example, during the progressive stage of psoriasis, it's appropriate to use ointments with heat-clearing and detoxifying properties for external application, while during the stable phase, one can use medications that have certain detoxifying and exfoliating effects.