This walkthrough will explain three different ways to complete Rendezvous in Rotterdam with the silent assassin rating.
Method 1: As the reporter
Get into the compound
Right at the start, run towards the entrance to intercept the reporter (Michael Marshall), sedate him and pick up his clothes and money. Then drop all of your weapons, and run right until you reach the main gate. Then wait for a few seconds and the guard will open the gate for you. Then the guard will then search you. After having been checked, enter the right entrance near the garage.
Kill Rutgert van Leuven
Now head straight, then you will be in the main room. Head right and enter the door leading into a large room. Head left and go into the bar area and talk to the bartender to receive a keycard. Follow the bartender until the office of the boss. Wait until the bartender leave the room, then talk to the boss. Fiber wire him when he opens the safe. Recover the photos in the safe. You may take the money and the Gold Desert Eagle as well.
Kill Klaas Teller
Quickly go back to the stairs, be sure you run into nobody, then go in the basement. There, you have to avoid the few guards patrolling. You have to kill the second target and get a new disguise. First at the bottom of the stairs head right passing the shooting range, then head left and enter the room at the end of the hall. If there are unavoidable guards on this route, take the longer way left. When you enter there will be corpses of bikers and strippers on the floor. Take one of the bikers disguise and exit the room and straight down the hallway in front of you, then enter the room. There you will find Klaas, kill him in anyway you like. (Electrocution / Knife / Meat hook / Firearm of your choice, though the last two are not recommended) You can also roam around the basement and loot weapons and ammo, just don't get near the guards and don't try to do something extremely stupid like smuggling a sniper rifle out.
When it's done, leave through the direct exit of the basement. Go through the gap in the wall and climb the fire escape to the second floor of the warehouse. Now avoid all guards and get out and go near the truck. The mission will end with Silent Assassin and you will get the Sawn-Off Shotgun Dual.
Method 2: As a biker
Get the disguise
At the beginning, follow the biker and the girl into the warehouse, just don't get seen. Now go all the way to the second floor, avoiding all guards along the way. In the room marked with a !, there is a biker prospect disguise. Take it, but beware, the girl nearby could see you and raise an alarm. Now take the fire escape out of the warehouse and enter the compound through the gap in the walls.
Kill Rutgert van Leuven
Now go to the garage entrance, but enter the front door, into the storage room. There is a power switch to your right, turn it off. A biker will come to investigate. Meanwhile, go from the left to avoid him and enter the now unguarded door. Just next to you, there's a ladder. Take it to the second floor. Now get to the main area, you will see Rutgert moving towards the last door on your side. Follow him into the room and fiber wire him before he enters the next room. Pick up the safe combination and (optional) Gold Desert Eagle. Now go to the safe room and get the photos from the safe.
Kill Klaas Teller
Now go to the basement through the double doors. For some reason, the biker prospect disguise will get your cover blown at some point. So get the biker disguise from the corpse room. Now fearlessly go and kill Teller. Loot weapons from the basement if you want to.
Take the direct exit of the basement. Again, stay away from guards and escape from the warehouse with Silent Assassin.
Method 3: Poisoning the tattoo ink
Entering the compound
Run toward the entrance to intercept the journalist. Syringe him and take his money but leave his clothes alone. Return the way you came but continue to the warehouse. Enter the warehouse and get the biker prospect disguise as in Method 2. Exit the warehouse into the alley between the warehouse and club house grounds. Take the rat poison between the two dumpsters. However be careful because there are two bikers armed with AK-74's patrolling this alleyway.
Get the keycard
Enter the storage room on the left side of the warehouse and head for power switch to cut the power. As the tall biker goes to turn power back on, exit the backdoor into alley right behind club house. Climb the stairs to roof. Enter the door to left to the secured second floor. Make way to Rutgert's office taking care not to be spotted. Hide behind the chair closest to safe. Hold the crouch key down and open the map. Then release crouch key and exit map. You should stay crouch until you move.
By now the journalist having recovered from the effects of the syringe has arrived to meet with Rutgert to obtain the photo (BETWEEN THIS, HE'LL GIVE A VISIT TO WASHROOM SEVERAL TIMES). Unable to produce the cash upon demand, Rutgert executes him and leaves the office. Now take the key card from him.
Kill Klaas Teller
Now head for the basement. Get the biker disguise from the corpse room and go to the room where Klaas is being held. Kill him in any way you like (electrocution recommended). If you loot the basement, don't take any non-concealable weapons this time.
Poison the ink
Make your way back to the stairs and head back to the second floor. Return to Rutgert's office and drag the journalist's body to the room to the far right of the second floor map--don't get caught be Rutgert. Sneak into the room on the top left and poison the tattoo ink. Then exit the door back to the roof. DON'T BOTHER TRYING TO HIDE BEHIND THE RED CURTAIN!
Watch through the keyhole as Rutgert receives yet another tattoo. Once Rutgert dies and the tattoo artist darts from the room, quickly go back in, take the safe combination and (optional again) Gold Desert Eagle, and drag Rutgert's body to where you stashed the journalist's body. Stay in the rooms on the top of the map as you go. The bartender will be searching all rooms on the second floor except the room to the far right of the map. This will require virtually perfect timing and lots of map recon to know where the bartender and tattoo artist are located.
Take the photos and escape
Once the bartender heads back downstairs, take the journalist's clothes, get the photos from Rutgert's office, and go to the first floor. Leave the club house and head for the main gate. Open the gate and make your way for the exit. The Mission will end with the silent assassin rating.