Have you ever played a new game on Goon Haven servers and got shot right in the face by some sprinter? Or are you a sprinter shooting down many noobs before they can hide behind walls?
For these reasons, I suggest that there be a 30 second waiting period a player can shoot anyone at the beginning of a game.
In the 30 seconds players have, they can build some walls in front of their bases entrance before the enemy can snipe them down. This will also attackers, who can gather a larger source of people before an assault.
Also, if both sides have defenses before the 30 seconds runs out, the battle will become a stalemate, ensuring that neither side has a really big advantage.
Best of all, having a 30 second postpone will keep all the pro's from sniping down all the pathetic noobs, who will at least have a small chance to defend themselves.