When startingthe game, you will have to complete the prologue mission. Once done, you will go to the Paladin plane to start the main missions. Here you can also start side missions by talking to your team. Talk to Grim to get four side missions to complete before you start the main missions. When you complete all of Grims missions, new gear will be unlocked under the "Customize Gear" option. You will now have all the stealth gear and can start Mission 1: Safe House. This is one of the fastest missions in the game, and if you complete it without killing anybody and stay undetected, you will get tons of money when you complete the mission. Once you finish the mission, you will be back at the plane. While on the plane, go to the "SMI Panel", and press A. When the map is displayed, press LB to show all missions. You will have the option to replay the "Safe House" mission. Replaying and completing this mission eight times will get you more than enough money to every planes upgrade and all of Sam Fisher's gear and weapons.