Precision contracts generally involve getting headshots, specific types of kills, and finishing missions or sections quickly. Please refer to this guide from M-Easy over at PlayStationTrophies for more information on all the contracts. Listed below are some additional strategies for the tougher precision contracts.

Headshots with weaker weapons: headshots with weak weapons such as pistols and SMGs don't always instantly kill your targets, so try to get as close as possible (possibly by using the ghost generator) before firing at the head.

Diplomatic Incident: the time limit for this mission is only 15 minutes, which doesn't leave a lot of room for error. You will need to rush through the first part of the level, stopping only to get a kill by destroying a flamethrower tank. When you reach Justus and Boris, focus on killing the soldiers with rocket launchers, as they are the only ones that can hurt Boris. When you reach the final courtyard, make sure you have an M80 to shoot down the dropship. Boris can't take that much damage in the final section, so again focus on the rocket soldiers. The timer will stop when you get in the elevator, not when you reach the bottom and trigger the cutscene.

Hostile Takeover: you will want to get the proximity mine kill right at the beginning of the mission, as there are plenty of enemies and mines in the area. The long range kills with the sniper rifle can really only be achieved during the stealth section with a few snipers. You only get one good chance to destroy an exo with a barrel; the first exo you encounter after getting outside the embassy. Resupply at the armory and get an M80 and then hit the exo with it twice. Then, lead it around the area and shoot at the explosive barrels when it gets close. You will encounter a few more exos during the final objective but they won't get near any explosive barrels.

Blood Money: the hardest part of this contract is clearing the initial landing zone with at least one Helghast soldier surviving. Rush through as quickly as possible, as more enemies will spawn if you take longer. Once you reach the vault, kill all of Grey's guards and then use the M2 to down her, allowing you to interrogate her for the last requirement.

Exit Wounds: this one can be pretty tough, as three of the requirements are problematic. You will want to use the STA-14, M80 launcher, frag grenades, the porcupine van-guard, and the supply armor so you can get more ammo. Only use the STA and frags for the majority of the mission until you reach the final battle; the timer starts as soon as you can attack Benoit. Use the porcupine and M80 to bring down the intruder, and use the STA to attack the other mercenaries. It is best to try and get the flying mercenary kills before the intruder goes down, as Benoit will eventually stop calling in reinforcements. With the M80 and porcupine the 10 minute time limit isn't too bad. Once Benoit is on the ground, attack the cooling cells whenever he walks near one to do some damage. Remember that you have limited ammo, so scavenge as much as you can from dead mercenaries.