Walk out left of the tree and walk behind him. Get to the second tree and wait for him to start his round. Go to the back and keep one of the two trees between you and the lone guard. Once out, head right and stay against the building. Wait in it until you're at the next sewer. a truck will stop that you can get in the back of. Wait for the guard to go into his room, then dash out into the roadway. At the other end is a guard and your weapons (crossbow). Run down the back side once the guard goes in. Make your way to the tree nearest the building. The sniper is in the tower with the lighted windows. Stay back behind the trees and head to your left. (The chocolates I haven't figured out yet either) Head out of the room and back out the way you came. Kill him with a head shot and take combination. Follow him to the room (it will be one of the front corner rooms, either up or down stairs, they all have exclamation points). Now check your map and watch where the white VIP goes.
Wait for the target by hiding in the corner and dropping him with a head shot when he enters again. When he leaves for the ballroom, walk into room and strangle the maid, dragging her body behind the desk. The target will be going back and forth between the ballroom and the room you're standing around the corner from. Take the bottom left door in the entryway. So go out the door to the left of the cook.
The champagne glasses are on the counter in the middle of the kitchen, but I haven't figured out how to use them yet. Head upstairs passing two doors on your left and one on right. There will be guards, but if you walk they may shout, but that's all. Got to the door in the wall and pick lock. Walk in between the buildings and time it to come out behind the sentry as he passes going left. Take room key (I'm still trying to figure out the room key and the champagne glasses we'll find soon). To your right at the beginning there is a waiter crying. On the title screen press XBAXBXA, Left trigger. If they are running down the flight of stairs the first guy will be wearing a red leather jacket, kill the guy behind him and run as fast as you can to the train station without being killed. Then run up the stairs ,turn left if they are still in the room, kill the guy on the opposite side of the table. If you're having trouble figuring out who you have to kill at the St.Petersbourgh stakeout what you should do is get to the building as quick as you can kill the guards out front silently. Get a "Silent Assassin" ranking on any mission to unlock the Silenced Ballers.