Reaper Resources Trick
Save your game upon reaching a new Reaper controlled region. Now explore the area, making note of all the resource locations. No need to engage in battle, just run from any enemies you contact and continue to scan for resources. Once you have a good idea of where they all are, reload your file and go gather them. You'll be saving yourself a great deal of fuel and wasted time with this strategy.
Exit War Room Scanner Trick
Here's an easy way to get a nice new weapon and armor, and have some fun doing it. Simply download the free Kingdoms of Amalur demo and play it. Doing so will unlock the two new pieces of equipment in Mass Effect 3, the Chakram Launcher and Reckoner Knight Armor. The armor increases your attack power in close quarters combat, while the weapon fires off powerful disc-shaped ammunition.
The location of every mighty shotgun that can be had in Mass Effect 3.
M-23 Katana: Starting weapon in the Priority: Mars mission.
M-27 Scimitar: Found within the main Turian camp, on the ground, during the Priority: Palaven mission.
M-22 Eviscerator: Found on the red couch during the Grissom Academy: Investigation mission.
M-300 Claymore: Found inside the left building within the abandoned camp during the Attican Traverse: Krogan Team mission.
Graal Spike Thrower: Found near the beginning of the Priority: Tuchanka mission, near the railing with the nearby guard.
Disciple: After you find the lone Asari during the Lesuss: Ardat-Yakshi Monastery mission, enter the combat room and clear it of cannibals to find this shotgun.
Geth Plasma Shotgun: Within the large combat area during the Priority: Rannoch mission, you'll find this gun to the right side of the area, near the entrance.
M-11 Wraith: Can be purchased from the Spectre Office for 250,000 credits.
Here are the locations and methods for obtaining the various assault rifles found in the game.
M-8 Avenger: You'll get this during the Prologue.
M-15 Vindicator: During the Priority: Mars mission, you'll find this rifle tucked away in a small security room just off the main hallway as you approach the archive chamber.
M-96 Mattock: Found in the hallway with the red benches while doing the Grissom Academy: Investigation mission.
Phaeston: You'll find this one in the Tuchanka: Turian Platoon mission. It's found near the bodies of some dead Turians which you'll come across after chasing off the Harvester.
M-76 Revenant: Found in a restroom during the Priority: Citadel mission. You'll come across a Combat Engineer working on a latch. Go ahead and kill him, and then search the area behind him to find the restroom, before continuing on.
Geth Pulse Rifle: Found during the Priority: Perseus Veil mission. It's sitting on a shelf in plain sight along your main path as you near the control room.
M-99 Saber: You'll find this during the Priority: Horizon mission.
M-37 Falcon: You'll find this during the Priority: Cerberus HQ mission.
There are but a few destructive submachine guns to be found in ME3, so make sure you don't miss any of them.
M-4 Shuriken: You'll find this gun during the Priority: Mars mission, inside the security room with Liara. Grab it before you activate the security console.
M-9 Tempest: Found inside the caves after defeating the husks and climbing the ladder during the Tuchanka: Turian Platoon mission.
M-25 Hornet: Upon taking the elevator up to the new area in the Priority: Citadel mission, look for this gun on the right side along with some other items.
M-12 Locust: Found in a lab early in the Priority: Horizon mission.
There's nothing quite as enjoyable as sniping your enemies from a distance, before they even know what hit them. Here's where to find all the sniper rifles that will let you do just that.
M-92 Mantis: Found on the ground to your right after descending the ladder during the Priority: Mars mission.
M-97 Viper: Found within the main Turian camp during the Priority: Palaven mission, resting on some boxes.
M-13 Raptor: Sitting on a bench on the level which overlooks the outer facility during the Priority: Sur'Kesh mission.
M-29 Incisor: Found on a ramp as you leave the first combat area within the Tuchanka: Bomb mission.
Javelin: You'll acquire this sniper rifle during the "Rannoch: Admiral Koris" mission.
M-98 Widow: You'll acquire this sniper rifle during the "Priority: Thessia" mission.
Black Widow: Paying 250,000 credits to the Spectre Office will get you this sniper rifle.
They may not have the swagger or destructive force of some of the other weapons in the game, but pistols can be just as useful for blasting away single foes. Here's where to find them all.
M3 Predator: The first weapon you'll come across, during the prologue.
Scorpion: You'll find this on the floor after reactivating the elevator power source during the Priority: Sur'Kesh mission. Grab it before turning the elevator back on.
M-5 Phalanx: Found lying on the ground during the Priority: Tuchanka mission, just before the large expanse of land where the Reaper will fire upon your team with its lasers.
M-358 Talon: In the C-Sec HQ encountered during the Priority: Citadel mission, you'll come across a darkened hallway which leads to four offices. One of these offices is locked, and can be unlocked by finding the computer console further down the path. Head back to that office to find this weapon.
M-6 Carnifex: Found waiting for you on a pipe in the red maintenance hallway during the Arrae: Ex-Cerberus Scientists mission.
Arc Pistol: This pistol will be given to you by Tali during the Priority: Geth Dreadnought mission.
M-77 Paladin: You can buy this one for the low, low cost of 200,000 credits from the Spectre Office.