Here is my current study plan. It has three aspects:
1. Define all of the unique printings. I am following a cronological plan. I have completed a look at the 1935-44 watermarks, and am now just beginning an indepth look at the Ministeriales (officials for the eight government ministries), to be followed by a look at the typographed stamps.
2. The plate varieties by value (from 1/2c to 20 pesos)
3. Postal History, also chronologically (rates, cancels, markings, entires, perfins, box receipts).