You will have the option to replay the 'Safe House' mission. When the map is displayed, press LB to show all missions. While on the plane, go to the 'SMI Panel', and press A. Once you finish the mission, you will be back at the plane. This is one of the quickest missions in the game, and if you complete it without killing anybody and stay undetected, you will get a lot of money when you complete the mission. You will now have all the stealth gear and can start Mission 1: Safe House. When you complete all of Grims missions, new gear will be unlocked under the 'Customize Gear' option.
Talk to Grim to get four side missions to complete before you start the main missions. You can also start side missions by talking to your team. Then, you will proceed to your plane to start the main missions. When you start the game, you will have to complete the prologue mission. Easy money, all weapons upgrades and gadgets at the start