Greetings, today I bring a personalized guide.
Its aim is to make your your team to take the win (That depends on how you are), I always win with this build as normal, also serves in ranked.
Hopefully my support has been in vain.

Quintessence (3): Greater Quintessence of Attack Damage +2.25 Physical Damage
Mark (9): Greater Mark of Armor Penetration +1.28 Armor Penetration
Glyph (9): Greater Glyph of Magic Resist +1.34 Magic Resist
Seal (9): Greater Seal of Armor +1.41 Armor

21 Points in Offense
4/4: Fury - Attack Speed
4/4: Deadliness - Attack Damage Per Lvl
1/1: Weapon Expertise - Armor Penetration
3/3: Havoc - Increases Damage Dealt
2/2: Lethality - Critical Damage
2/2: Brute Force - Attack Damage
1/1: Frenzy - Grants 10% of Attack Speed for 2 Secs after landing a critical hit
3/3: Sunder - Armor Penetration
1/1: Executioner - Increases Damage Dealt by 5% to targets below 50% health
9 Points in Defense
4/4: Durability - Health per Lvl
3/3: Hardiness - Armor
2/3: Resistance - Magic Resist

1. Berseker Graves: Is a good start, movement speed and attack speed
2. Blodthirster: You need lifesteal, so that when they hit you much you can restore your health
3. Phantom Dancer: The movement speed, critical and attack speed are so overpowered
4. Infinity Edge: The great critical damage
5. Last Whisper: The armor penetration, of course!
6. Guardian Angel: The defense serves to resist, and you have more chance to live

HEADSHOT (Passive)
Every 8th / 7th / 6th basic attack deals 150% damage to a champion or 250% damage to a minion or monster. Attacks from brush increase the attack counter by two instead of one. Headshot's counter does not increase from attacking turrets.
PILTOVER PEACEMAKER (Q) Always, when available
ACTIVE: After a 1 second casting time, Caitlyn fires a projectile that deals physical damage to all targets it passes through. Each target hit after the first takes 10% less damage, down to a minimum of 50% of the original damage.
YORDLE SNAP TRAP (W) After Q
ACTIVE: Caitlyn sets a trap at target location that activates after a brief delay. When an enemy champion comes within 67.5 range of the trap, the trap snares and deals magic damage to the enemy over 1.5 seconds, also revealing the enemy for 9 seconds.
Caitlyn can set up to 3 traps and each lasts 4 minutes. Traps are visible to both allies and enemies. If she sets a trap when three are already placed, the oldest trap will deactivate itself.
90 CALIBER NET (E) Not all the time
ACTIVE: Caitlyn fires a net, knocking herself back 400 units in the opposite direction. The net will deal magic damage and slow the first enemy hit by 50%.
ACE IN THE HOLE (R, Ultimate) 3 Times
ACTIVE: Caitlyn channels for 1 second, providing vision of target enemy champion. She then fires a 3200-speed homing projectile to the target, dealing physical damage to the first enemy champion it hits. Other enemy champions can intercept the bullet.

DEFENSIVE


The shield works to fight, defense and run.
The flash works to run and run to get a kill



Cleanse and Flash are defensive too.

DAMAGE/KILLER

Ignite: When you grab a victim, this spell can throw your enemy and complement the damage to get a point.

It is excellent throwing Piltover peacemaker, because damages all enemy team, leaving them defenseless.
The spell yordle snap trap, used to trap an enemy, this can work in an ambush or a fight between computers.
The 90 Caliber Net spell serves to slow down, can be used to slow down an enemy so they do not catch your teammate.

1. Approximate Events
With the spell Piltover Peacemaker, can you approximate the movement of your enemy easily, how?, Releasing the spell in the direction he's going to go.
You can also serve with Yordle Snap Trap spell, can you approximate the movement of your enemy easily, how?, Releasing the spell ahead to get caught and you get the victim.
2. Run and Attack
With the spells Piltover Peacemaker and 90 Caliber Net, first release the spell 90 Caliber Net and then the spell Piltover Peacemaker in the direction of the enemy, this is a leak and damage.

1. Early Game: Be safe, just last hit in the minions
2. Mid Game: You have damage, so, just hit.
3. Late Game: TONS OF DAMAGE! HIT! HIT!!!