A:
B:
C: Acrobatics, Reflex
D: Weapon Proficiency (Sword or Spear), Ride or Throw, Stealth 
E: Armor, Survival or First Aid

This is your starting skills. At any point, no more then 3 can progress 1 grade. Meaning that armor cannot be rank c, because it has gone up two ranks. It can however, be rank d, so long as only two other have progressed. So, as example, you could do this.

A:
B: Acrobatics
c: Reflex, Weapon Proficiency (spear), Stealth
D: Ride
E: Armor, First Aid

As such, you chose to advance Acrobatics, Weapon Prof, and Stealth, meaning your character is able to traverse difficult terrain better, handle his spear with greater ease, and possesses more skill in stealth. At no point can you lower a skill to raise another. So if you tried to drop ride lower to raise reflex, it would not be allowed. As such, the skills above are just an example, set your character up how you want. But that's the overall ruling on skills.

[@Voltus_Ventus]