Hey Guys, this is a rather versatile Caitlyn build that can be used is various ways depending on your play style. I will also explain various tricks and techniques when playing Caitlyn.

Firstly Caitlyn is a extremely good DPS carry that strives on picking off champions in team fights. She is quite squishy in all stages of the game, but with good technique and use of your skills death wont come easily to you. Caitlyn is suitable for all lanes, but I find she is best in mid lane, due to her strong harass early game and excellent last hitting capabilities on minions. Don't be a afraid to use your range to its full advantage and say out of the centre of team fights. Caitlyn should say back from the team fights, usually next to or near where your support champions are, she can do this due to her massive range, thus still being involved in the fight.

Runes for Caitlyn are pretty simple. Armor peneration Greater Mark of Desolation and Greater Quintessence of Desolation is quite useful early game and its mainly needed and used for late game. Reason for choose this over Greater Mark of Attack Damage since they almost have the same effect in early game, but armor penetration late game is more useful since its harder to obtain compared to getting attack damage. Mana Regeneration Greater Seal of Replenishment and Greater Glyph of Replenishment is needed so you can spam your abilities early game for harass and minion kills. Its also quite handy as it helps you to always have a reasonable amount of mana for your ultimate. Other Seals and Glyphs that can be quit useful include: Greater Seal of Attack Speed / Greater Glyph of Attack Speed you can never have enough attack speed with Caitlyn just make sure you have heaps of attack damage to compliment it. Greater Glyph of Magic Resist and Greater Seal of Armor can be quite useful for early and late game survivability.

This is a pretty stock standard mastery set up, but of course its will vary to you depending on your choice of summoner spells. the reason for 21 - 6 - 3 and not 21 - 0 - 9 or 21 - 9 - 0 is because I find durability is key and very important for early game, so you can push and stay in your lane longer, thus getting more experience rather than going back to base every-time your health gets too low. 21 - 9 - 0 could be useful picking up Nimbleness with Greater Seal of Evasion.

Starting Items:
You can choose a multiple different starting items, I find Doran's Blade most useful in laning so you can last hit easer and the bonus lifesteal can be a saviour. Vampiric Scepter is good for longer lane survivability, more used for those reckless players. Boots + Health Potion times 3, this is for when your not in mid where its harder to suruvive with only just a doran's and vampiric scepter depending on how much harass you deal or receive.

Boots:
fairly simple for that added attack speed.

Main:
Building and buying the 3 items in-game that only use the B. F. Sword due to the massive damage out-put you will receive. You could also use Last Whisper or Madred's Bloodrazer for a more tank destory build for taking down players.

Survivability:
Banshees is just a good overall item for defense for many players.

When laning in mid place your traps horizontal across the lane at their your side of the lane (for defensive play) or on the Enemy side (for aggressive play). This is useful for lane control. If on Top or Bot place them in the same way or in bush to prevent ganking.

Another trap techinque is to place them at the base of the Enemy tower, so when at lower HP you can get a quick Piltover Peacemaker on them. (easy kill)

Save your ultimate for the end of team fights and or to pick off those who try to escape.

Your 90 Caliber Net can be used to pass through walls and obstacles.

Direct hits with Piltover Peacemaker course the most damage (the first target hit), keep this in mind when farming and trying to harrass.

Your traps deal little to no damage and are more used for Crowd Control (CC).

If your in a 1v1 til death place a trap at their feet to gain a few seconds over your enemy.

Remember your ulitmate goes through terrain and is block-able only by champions, you also must have line of sight to use.

Focus those Champions who will focus you first or those champions who deal massive splash damage. Go for the tank last.