The Ministry of Industry, Trade and Tourism has published a guide to public procurement especially for small and medium-sized enterprises, which can be found at the following link
The National Commission for Markets and Competition has published a practical guide on public procurement specifically aimed at compliance with the principle of free competition, which can be found at the following link
The Independent Office for Regulation and Oversight of Procurement has published several guides on public procurement, which you can consult at the following link .
Public sector entities must schedule the public procurement activities they will be undertaking in a financial year or over multi-annual periods, and must make their procurement plan known in advance by means of a prior information notice that includes at least those contracts that will be subject to harmonised rules.
There are also some specific plans, such as the Public Procurement Plan of the General State Administration, its autonomous agencies and Social Security administration entities.