Human, 1st-Level Warrior

Medium (Humanoid (Human)) CR 1/2
HP 6, hd1d8+2 AC 16 (+4 scale mail, +2 heavy shield), touch 10, flat-fooded 16 Fort +3*, Ref +0*, Will ?1* Speed 20 ft. in scale mail (4 squares); base speed 30 ft. Initiative +0 Spot , Listen
Standard attacks BAB +1, Grapple +2
Attacks
Full attack: Longsword +3 melee (1d10+1/19-20) or Longbow +1 ranged (1d8/x3) or lance +2 melee (1d8+3/x3)
Special Attacks/Qualities
Human traits
None
Skills Handle Animal +4, Ride +4
Feats Weapon Focus (longsword) plus Human Extra Feat
Str 13 Con 12 Dex 11 Int 10 Wis 9 Cha 8
Alignment Any, Environment Any, Organisation Squad (2?4), Platoon (11?20 plus 2 3rd-level sergeants and 1 leader of 3rd?6th level), or Company (30?100 plus 30% noncombatants plus 1 3rd-level sergeant per 10 adults, 5 5th-level lieutenants, 3 7th-level captains, plus 30% heavy warhorses)

Humans use sophisticated and flexible tactics against their opponents. The bulk of human troops are infantry. Infantry units use longspears or other polarms. These units have the Tower Shield feat (units add a tower shield, gain +4 to AC, and make attacks at -2 while employing the tower shields). Infantry's use the aid another combat action to both fight defensively and increase their chances to hit make them deadly on the battlefield. Some infantry units use the longspear's reach as their primary defense. These units have the feat Weapon Focus (longspear).
Human infantry often forgo heavy armor for speed. These units employ the Endurance feat and forced marches, enabling them to move vast distances while still able to fight at peak performance. They use this feat to exhaust enemy troops through days of marching, giving them a tactical advantage on the battlefield.
Humans frequently employ horses in cavalry units. Mounted infantry use horses to move quickly while avoiding exhaustion, but not in actual combat. Mounted archers use their mounts to harass the enemy with bows. Lancers actively fight from horseback, using their devastating charge to break enemy formations. Mounted archers and lancers have the Mounted Combat feat. Lances do double damage when used in a charge.
Archery units engage opponents before infantry units close to melee range. Archery units have the Weapon Focus (longbow) feat. Many light infantry units specialize in using javelins or slings.
Most humans are not warriors. Civilian humans usually take the Skill Focus feat in their area(s) of expertise.
Human Traits (Ex): Humans posses the following racial traits.

• Medium: As Medium creatures, humans have no special bonuses or penalties due to their size.
  
• Human base land speed is 30 feet.
  
• 1 extra feat at 1st level.
  
• 4 extra skill points at 1st level and 1 extra skill point at each additional level.
  
• Automatic Language: Common. Bonus Languages: Any (other than secret languages, such as Druidic). See the Speak Language skill.
  
• Favored Class: Any. When determining whether a multiclass human takes an experience point penalty, his or her highest-level class does not count.
  

The human warrior presented here had the following ability scores before racial adjustments: Str13, Dex11, Con12, Int10, Wis9, Cha8.
Habitat / Society
putting the beastie into context within its own society - one for the simulationists, munchkins can simplify this one to 'mooks / big boss'.
Ecology
putting the beastie into context within the ecosystem - one for the simulationists, munchkins can simplify this one to 'best rare / charbroiled, feathers worth x in a reasonable city, etc'
ecology is also a good place for geography - note some places in Cerilia (or outside) where your beastie can be found, or is rumored to exist.
Variant X
All good beasties have various divergent versions, sometimes bigger, sometimes smaller, sometimes with a botanically fascinating ability to spit lethal poison. Whatever floats your boat.