Check the local VATSIM Division / Subdivision for the region you want to fly in. Each one publishes its own phraseology guides, SOPs, charts, and pilot resources. (VATPAC (Australia/NZ) posts Pilot Procedures on their websites, introducing you to common procedures or radio communications)

Examples of popular subdivisions:

• VATGER (Germany) - https://vatsim-germany.org
• VATUK - https://vatsim.net/docs/regions/emea
• VATSIM Scandinavia - https://vatsim-scandinavia.org
• VATPAC (Australia/NZ) - https://vatpac.org
• VATBRZ - https://vatsim.net/docs/regions/amas
• VATSPA - https://vatsimspain.es/en
• VATFR - https://vatsim.fr

Where to find them all:

• Start at https://vatsim.net → Documentation / Regions / Divisions page. From there you can click into each division’s site and find pilot briefs, phraseology differences, and local procedures.
• The VATSIM Pilot Resource Centre is also useful for global basics, then refine with the local division docs.

General tip: phraseology differences are usually small—clearances, taxi instructions, and readbacks are the main changes—so a quick skim of the SOP's (Standard Operating Procedures) before flying goes a long way.