Diplomats 

The role of the diplomat has been around since before the 15th century Earth.  The diplomat has been the one whom sought out peaceful solutions when conflicts would arise.  They would hammer out trade agreements and would be in the core of alliances as they were being created. 

In the world of Star Trek, diplomats have been in the core of all alliances and non-aggression treaties, in trade agreements and tools for the military, as well as provide cultural expertise and mediation between societies.  Diplomat's primary tool of choice is not a phaser or a sword, but their words.  The main difference is that you have a variety of societies that can be represented, such as the Ferengi Corporation, the Klingon Empire, the Dominion, or the Trill Consultant.  Each of these ‘flavors’ of diplomacy add a delightful and savory twist to diplomacy.
 
The labels of the diplomat
 
Being a diplomat requires you to play many various roles in Startrek.  Each of those roles provides a unique angle that will improve the realism and the quality of your log entries as you write.  Though these are by far not all the roles a diplomat could possibly play, these are the most common that are used.
 
Diplomat- A

Diplomat is an individual whom merely seeks out peaceful solutions to conflicts.  Any person can be an ambassador.  Frequently, the role of diplomat falls on the shoulder of the military.  It is a common occurrence that a Captain of a starship forges out a neutral agreement with a new species.  
 
One of the most common types of diplomat is that of the free-lancer.  A free lancing diplomat serves no government.  They mediate for their own personal conviction whether it is for nothing more than money, or as powerful as personal beliefs, convictions, or random chance.
 
Politician-

One of the diplomatic roles that undoubtedly must be played is that of the politician.  A diplomat carries a hefty portion of diplomatic power.  Politicians are activists of a series of beliefs and obligates themselves to actively pursues their beliefs.  Further, a politician is frequently used as a liaison to the public and the media.  They will be asked to speak for the military whenever topic come up that the public must know about.
 
Mediator-

The role of the mediator works very closely with that of a Diplomat.  The Mediator is a person whom serves and objective role between two or more parties.  Mediators lean towards events where hostility is not in the equation.  For example, a mediator will hammer out a trade agreement where a failed result does not mean war, but simply no trade will occur.
 
Ambassador-

One of the most important role is a diplomat is one that is commonly mistaken for the diplomatic role.   Being a diplomat does NOT necessarily mean you are an ambassador.  An ambassador is normally a citizen and representative of a government that is sent to a foreign land whether friend or foe to speak for the government.  The Ambassador will usually be given an embassy (a place to live and work) to manage and control in the foreign territory.    Their assignment is usually a long-term assignment, unlike a diplomat.  Further, the levels of ambassadorship go from a low level ambassador to high level.
 
A low-level ambassador usually is a mere aide to the main ambassador.  Frequently, he or she is sent to do the basic task of an ambassador, such as maintain the staff of the embassy, ensure documents are prepared on time, and serve as a witness to a negotiation.   The high-level ambassador is usually the one whom is the primary representative to speak.  He makes the decisions and is ultimately responsible for the work he accomplishes.
 
The most important privilege to the ambassador and is reserve solely to this role is diplomatic immunity.  In essence, being an ambassador means that you are exempt from all search and seizures or prosecution from the foreign government.  This includes all communications, activities, and actions.  Bear in mind that this privilege is not given to the freelancing diplomat, only an official government representative in a foreign territory.