I’ve been playing Call of Duty 4 (CoD4) for xbox 360 for about 5 months now. I’ve gone prestige many many times. People often ask me How do you gain CoD4 rank so fast? Its pretty simple. HEADQUARTERS games.
It gives TONS of XP and its really fun to play. Make sure you complete your weapons challenges and basic challenges when you hit the appropriate level. You get +5 points repeatedly when you are dead or alive while your team holds the HQ. Plus you can get a TON of kills because the game lasts so long.
So my straight up answer to “What is the fastest way to rank up in call of duty 4?” play headquarters, and play it often.