This is a simple suggestion. To aid newer players to the game and multiple game types, I propose that there should be either one of the following:
a) An instructional page between starting the game and choosing a team which explains the rules and objectives of the game type being played.
b) A instructional page within the game, toggled by pressing a button such as 'h' with the above information.
These are simply to aid newer players in the game who may not know exactly what they are doing in each game type as they play, and to give them hints and help in achieving the objectives. It is to help stop players from blindly going for kills and nothing else because they don't actually know the aim of the game.