Each Class has it's own set of Skills to choose from to enhance particular Actions associated with that class. (Ex: Lvl. 1 Ranger with the Tracking skill grants the ability to sense game numbers in tiles as well as improves chance of Hunting success.)

Skills can fall into three categories:

1) Innate Skills that are inherent to a class and do not need to be acquired on leveling up.

2) Base Skills that can be acquired as soon as a class is chosen.

3) Upgraded Skills that can be acquired if the corresponding base skill is obtained first.

Skill Skill Type (Req: if applicable)
Marksmanship Innate
Tracking Base
Pathfinding Upgraded (Tracking)
Forestry Base
Treefriend Upgraded (Forestry)
Wildhome Base
Outlander Upgraded (Wildhome)
Foraging Base 
Swift Scavenger Upgraded (Foraging)

Skill Skill Type (Req: if applicable)
Soilreading Innate
Speedreaper Base
Blinkreaper Upgraded (Speedreaper)
Threshing Base
Seedbank Upgraded (Threshing)
Mulching Base
Terramancy Upgraded (Mulching)
Adaptation Base 
Scythe of Saturn Upgraded (Adaptation)

Skill Skill Type (Req: if applicable)
Geomantic Signs Innate
Excavation Base
Deep Mining Upgraded (Excavation)
Aesthetics Base
Fine Artistry Upgraded (Aesthetics)
Customization Base
Mastercraft Upgraded (Customization)
Careful Planner Base 
Architecture Upgraded (Careful Planner)

Skill Skill Type (Req: if applicable)
Animal Friend Innate
Tailoring Base
Master Clothier Upgraded (Tailoring)
Hearthtending Base
Homesteading Upgraded (Hearthtending)
Calming Presence Base
Soothing Aura Upgraded (Calming Presence)
Watchful Guardian Base 
Fenrisbane Upgraded (Watchful Guardian)

Skill Skill Type (Req: if applicable)
Magician's Tome Innate
Herbology Base - Sorcery
Mycology Base - Sorcery
Cleromancy Base - Arcane
Book of Thoth Base - Arcane
Cleansing Rites Base - Theurgy
Sanctify Base - Theurgy
Scrying Base - Arcane
Humble Aspect Base - Theurgy
Weatherlore Base - Sorcery

Skill Skill Type (Req: if applicable)
Martial Training Innate
Tough Base
Unstoppable Upgraded (Tough)
Comet Arc Base
Meteor Shower Upgraded (Comet Arc)
Apprentice Smith Base
Journeyman Smith Upgraded (Apprentice Smith)
Expert Fencer Base 
Quicksilver Reflex Upgraded (Expert Fencer)

Skill Skill Type (Req: if applicable)
Seal of Silence Innate
Thiefcraft Base
Dark Gadgetry Upgraded (Thiefcraft)
Sticky Fingers Base
Whisperhands Upgraded (Sticky Fingers)
Opportunist Base
Crippling Strike Upgraded (Opportunist)
Arms Dealer Base 
Shadowrunner Upgraded (Arms Dealer)