Go to a fence that buys metal and sell all of your loot. Go to your landlord's stash nearby Heartless Perry. Get the purse of coins (worth 50 g), then go around town and pickpocket purses from unsuspecting citizens. Whenever you get a purse it will say it is worth 25 g, but it will actually be worth 50 g. You can only do this once a night. Collect as many purses as you can. Once you sell those purses to a fence, any other purses you collect that night will be worth their regular amount.
When you first arrive at the docks, go towards the store. Stop immediately after you pass the Quarantine gate. There is a box in front of you. Destroy it. Go down the ladder and follow the stairs.
Slightly tilt Left Analog stick to glide across the floor and it will appear that Garrett is surfing.
Use a mine or be extra careful when sniping Keeper Guards. If sniping, you must hit them in the back of the head. If you are stealthy enough, you can try backstabbing them, because the blackjack has no effect on them.
If a Zombie is unaware of you, a single flashbomb will kill it. If it is aware, two are all that is required.
If multiple undead or Hammer Haunts are on a floor, toss down a Holy Water into a doorway. Then, lure the undead to chase you and run across the holy water. The undead will follow, killing themselves on the Holy Water. This is a good way to conserve Holy Waters.