MGS4 - Big Boss Hard - New Game
Act 1
Red Zone NW Sector
Red Zone
Militia Safe House
Urban Ruins
Downtown
Advent Palace
Advent Palace (Frogs)
Crescent Meridian
Millennium Park
Act 2
Cove Valley Village
Power Station
Confinement Facility
Vista Mansion
Research Lab Facility
You can make an hour long video explaining this fight. The main points are her damage caps, damage thresholds, phases, and positioning. If going for Big Boss Emblem, be careful not to kill the unconscious Frogs.
Mountain Trail
Mountain Trail Riverside
Drebin's APC
Marketplace
Act 3
Midtown S Sector
Midtown NE Sector
Midtown N Sector
Church Courtyard
You can damage 25% of her health during the bike chase sequence. Strats change slightly depending on NG, DP count, and NG+. Not much variation dependent on difficulty.
Echo's Beacon
Act 4
Heliport
Snowfield + Heliport
Tank Hangar + Canyon
Nuclear Warhead Storage Bldg 1F + B2
Nuclear Warhead Storage Bldg 1F
Snowfield & Communications Tower
You can be more aggressive on the lower difficulties and take the alert/damage from the frogs. It turns into a high risk, high reward, since Wolf will see you as well. On Liquid Easy she will always spawn behind the wall (@2:08 mark on the video).
Blast Furnace
Casting Facility South
Casting Facility North
Underground Base
Underground Supply Tunnel
Surface Tunnel
Port Area
Act 5
Ship Bow
Command Center
The frog skip before the Mantis fight will not work on Liquid Easy since the frogs are instantly knocked out with a tranq. All other difficulties will be the same.