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.
You can get the "Distraction Tactician" achievement almost anywhere in the game, but Mission 4: Private Estate is a good place to get it. At the start of the mission, search for a guard, and hide behind a nearby object. Then, press Back to make some noise and lure the guard to you. When the guard gets close, press X to eliminate him.
"Enhanced Lethality Demonstrated" achievement
Play Mission 2: Insurgent Stronghold on the Rookie difficulty. A couple minutes after the mission begins, you will have to go under a wooden bridge. At this point, you should have a full execution meter. While you are under that bridge, shoot at it until the guards hear you. This will make them group up, which is what you want to happen. They need to be as close as possible together. There is also a checkpoint in that area -- so you can keep retrying, if necessary. When you reach the other side of the bridge, go through the building, up the stairs, and wait at the window outside. Wait until the two guards inside the house and one from the outside are in your line of fire. Mark them with RB, and use your execution to kill three enemies at once. Before shooting them, throw some flashbangs so the other enemies will not attack you. Once done, quickly kill an enemy with hand-to-hand combat to fill up your execution meter, and mark and execute the remaining three enemies. Note: You must equip the strongest armor in the game or else the enemies will kill you. Activate the sonar vision on your goggles to see enemies quickly.
"Evidence Concealed" achievement
When you kill the first enemies in Mission 1: Safe House, you will be in an alley. There are six enemies and five containers in this area. One container is in the alley, and four are in the building you need to enter. Eliminate all of the enemies, and then put one in each of the five blue containers to get the "Evidence Concealed" achievement.
"Hostages Secured" achievement
At the end of Mission 7: Transit Yards, after defusing all the bombs, you will be in a train with a few enemies and civilians. Once you reach the end of the train, two enemies will take hostages and use them as human shields. If you get to close or start shooting, they will kill the hostages. To save them, throw sleeping gas. You can purchase sleeping gas on your airplane (headquarters) at any time. Alternatively, you can also mark the enemies and use your execution ability to kill them immediately.
"Hostile Shield Secured" achievement
At the end of Mission 6: Special Missions HQ, you will encounter an enemy with a shield. A short cutscene will start playing when you enter the room. Eliminate the other enemies, and let the Infantryman get close to you. Then, shoot his shield until he breaks down. You will then have a couple of seconds to get behind him and eliminate him with hand-to-hand combat by pressing X. Pick up his shield to get the "Hostile Shield Secured" achievement.
"Mission Footprint Zero" achievement
Mission 1: Safe House is one of the easiest and shortest missions in the game. Play this mission on the Rookie difficulty. The enemies will not spot you as easily. You also may want to attempt this after you have bought certain equipment to make things easier. You can replay all missions at any point in the game (even after completing the story). When attempting to get the "Mission Footprint Zero" achievement, the enemies never can shoot at you or tigger an alarm. Their "attention meter" (the half circle that fills up when they see you) may never turn red. If it turns red, you have been detected and need to restart. If the half circle turns all white, you are still fine and can proceed. As long as you kill enemies before their attention meter turns red, you will be fine to proceed.
"Tri-Rotor Functionality" achievement
Just after Mission 6: Special Missions HQ begins, you can see some surveillance cameras. Hide behind a wall, and release your Tri-Rotor drone. Steer it to the camera, and press X to shoot a sticky shocker dart. This will destroy the camera, and you will get the "Tri-Rotor Functionality" achievement. Note: You can purchase the Tri-Rotor drone on your airplane (headquarters) for $72,000. It is not a requirement to upgrade it to get this achievement.