The Skill Deck consists of 6 tiers. At character creation you start with 2 tiers with each tier having 3 skill slots. Each tier has up to 5 skill slots. The image below has highlighted the tier unlock at level 5 and the column unlock at level 10. Additional tiers and columns unlock as you progress in fame level. When you start the game your Skill Deck has 2 available Tiers with 3 slots in each one of them. When you reach Fame level 5 your Skill Deck will have 3 available Tiers with 3 slots in each one of them. Update image below.