1. Walkthrough
1.1. Great Success – Gain S+ on all U.S.S. mission on Professional difficulty

2. Collectibles
2.1. All Raccoon Mascots

3. Miscellaneous
3.1. Organic Shield – Kill 5 enemies consecutively while using a zombie as a shield.
3.2. Tongue Tied – Kill a Licker that is grappling a teammate
3.3. Chaos Averted – Kill an infected teammate with a headshot

Great Success
Gain S+ on all U.S.S. mission on Professional/Veteran difficulty
This Walkthrough will guide you through all 7 missions from start to finish. It was played on professional (which is the highest difficulty) in singleplayer and the S+ rank was obtained in all missions.

I do strongly recommend to play as spectre. Fully upgrade his passive abilities to find the collectibles a lot faster. If a collectible is nearby it will be highlighted. Only mission 5 and 7 should be played with other characters. Use Lupo in mission 5. Fully upgrade all of her passive abilities and her active ability called Super Solider. This allows you to become immortal for a short amount of time which will be extremely helpful during certain parts of the mission. Use Vector in mission 7 and make sure you have both his passive abilities maxed out. Select his active ability called camouflage. It’s going to be a great help during the part where Leon is trying to snipe you.
Always use the juggernaut shotgun as your primary weapon. It is super effective on short ranges. Choose the Samurai Edge as your secondary weapon and use it on middle to long ranges against soldiers. It’s quite accurate when shooting out of cover and the rate of fire is the best of all available pistols.

Mission 1 – Containment

Requirements for S+ in single player:
Kills: 32
Deaths: 1
Items Collected: 12
Clear Time: 25:00

My score:
Kills: 41
Deaths: 0
Items Collected: 13
Clear Time: 18:58

Mission 2 – Corruption

Requirements for S+ in single player:
Kills: 150
Deaths: 1
Items Collected: 20
Clear Time: 35:00

My score:
Kills: 193
Deaths: 0
Items Collected: 32
Clear Time: 29:08

Mission 3 – Lights Out

Requirements for S+ in single player:
Kills: 110
Deaths: 3
Items Collected: 20
Clear Time: 35:00

My score:
Kills: 129
Deaths: 1 (I cut the scene out where I died)
Items Collected: 29
Clear Time: 30:16

Mission 4 -Gone Rogue

Requirements for S+ in single player:
Kills: 150
Deaths: 2
Items Collected: 20
Clear Time: 35:00

My score:
Kills: 174
Deaths: 0
Items Collected: 25
Clear Time: 31:19

Mission 5 – Expendable

Requirements for S+ in single player:
Kills: 150
Deaths: 1
Items Collected: 17
Clear Time: 30:00

My score:
Kills: 155
Deaths: 0
Items Collected: 12
Clear Time: 29:33

Mission 6 – Redemption

Requirements for S+ in single player:
Kills: 100
Deaths: 3
Items Collected: 16
Clear Time: 35:00

My score:
Kills: 124
Deaths: 0
Items Collected: 17
Clear Time: 24:55

Mission 7 – End Of The Line

Requirements for S+ in single player:
Kills: 150
Deaths: 2
Items Collected: 8
Clear Time: 30:0

My score:
Kills: 183
Deaths: 0
Items Collected: 8
Clear Time: 19:38

Raccoon City Mascot
Collect all 7 Raccoons.
The raccoon collectibles look like real raccoons. There are 7 of them in total, one per mission (from mission 1-7). Finding them will give you some nice bonus XP.

Organic Shield
Kill 5 enemies consecutively while using a zombie as a shield.
You can do this pretty much everywhere if there are enough zombies nearby. When you encounter zombies for the very first time in the entire game (Mission 2) you can see how a couple of them are gutting a dead body. Grab one of the other zombies in the room and quickly shoot the explosive barrel near the door. It is not necessarily needed to kill 5 at once. Only 5 in a row while using one zombie as a shield (can also be done with a pistol instead of explosions).

Tongue Tied
Kill a Licker that is grappling a Teammate
The first spot to do this is at the end of mission 2. Here you will encounter lickers for the first time and they keep spawning until you move on to the next area. Try to focus on one licker only and go to the back of the room where the explosive barrels are. A symbol will appear above your teammates head when he / she is being grappled (the symbol looks like a hand). Try to keep the licker in focus and quickly shoot the nearby explosive barrels as soon as it starts the grappling attack. The licker has to die while it is grappling! Alternatively, you can use your weapons instead of the explosive barrels, but the barrels should kill the licker faster.

Chaos Averted
Kill an infected teammate with a headshot before they become a zombie in any mode.
This can be done everywhere when zombies are around. Just don’t help your team members and wait until they get infected by zombies. If members are infected you can see a purple biohazard icon above their head. Just kill your ally with a precise headshot.