Before you contact a GM to report a problem or complain about another player's behaviour
Explain the problem in the “Universe” channel. Perhaps another player has encountered and solved it.
Verify that the problem is recurring and, if possible, determine under what conditions it is occurring.
Think of giving as much information as possible, so, put links to screenshots :) because very often, you will be asked for screenshots: of the Missions window (key [J] ), (if the problem concerns one of the 11,000 missions), showing the content of the sys info window, the inventory or a chat window (depending on the case)...