This guide is ment for Catwoman laning, whether it be top or bot.
Catwoman is an AD caster with high mobility to escape and catch fleeing enemies with her E / W combo. 

At level 1 i take Nil weapon because it gives her much needed 75 HP and 5 HP in return every basic attack +10 AD.
Depending on who youre laning against, her Q will return the 5 HP because it applies on hit effects (Acts as a basic attack). I also take Tektite Vile because with her high mana cost W and constant E/Q combo, she becomes mana starved and vile is the most cost efficient item because it refills 3 charges every back.

Get to level 2 and take your E skill next(Max E second because it provides your Q with a huge % steroid per level). Taking E will not only allow you to have an escape incase of early jungle presance, but comboing it with your Q gives your Q an extra 25% more damage to harrass the enemy. Hiding in a distant stealth pad walking out E towards them and Q with max distance. Be sure there is no enemy jungler before doing so, if so just Q at max range to ensure your E is up for escape purposes.

level 3 take Q again for max harass. (Max Q first because its your highest burst skill)

level 4 take W. W is a great skill and if used at the right time will grant your lane a kill. Do not use W to harass with. Only use it when you are sure you can secure a kill or at least push your opponent out of lane. Do this because of the high mana cost. Now, when you are ready to use W and secure the kill, you can E to tumble, then W to knock your opponent down for .5 seconds. Depending on who your support or jungler is , if they have super strength and you can trust them to land it, you may want to just stick with the E/Q combo and W to slow them, But thats situtational and the knockdown is there at your disposal.

Level 5, take Q again, if you have 1,000 gold and your lane is pushed go B and buy Jokers crowbar immedietly. Starting this item whether you think its going to be a long game or not or getting kills... its a potential 75 AD, for 1,000 gold, it doesnt get any better than that.

level 6. congrats, youre now ungankable, unless its a nightmare batman, stay warded. You're still not bursty enough to catch your enemy by surprise, but with a couple E/Q combos, you can then do this rotation and secure a kill with them at 3/4 hp. E / R / Q / E / W / E / Q / E. You can do this safely not knowing where the jungler is because at first sight you can just spam E to get away because her Ult (R) makes (E) only have a 1.5 seconds cooldown.(unless its a nightmare batman, then just try and secure he kill and type "worth" in all chat like everyone else)

Continue maxing Q then E and R(when available) and doing that roatation. Now I want to talk about her items.

Started Nil weapon and Crowbar as stated before. Next, I was to rush Deashot's Visor to atleast tier 2. Since Catwomans cooldowns are so short, spamming abilities will grant more bonus power from this item, giving you more sustain and allowing you to use E/W/Q combo more to harrass with 0 damage taken.

My 3rd item I want to get to tier 2 for 2k gold is Psi-Scemitar. The passive on this item is like Sheen (if you've ever played LoL). After using a skill (E) your next attack will deal an extra 100% of your base AD. with a 2 second cooldown? Pfft all day. After you use E you have 5 seconds to use Q. Doing so (Around this level with roughly 120 AD) you'll deal an additional 78? damage. At level 3 it does 150% base AD. This is where all of your burst is going to come from early game.

Next item, should be situational. now that youre doing massive burst damage, and their team is noticing you more, you may want to build some HP or resistance with a Ra Al Ghul's robe or max Hawkmans Harness. If they still havent decided that youre a threat or you are sparing you R halfway through fights, you can finish off Deadshots Visor. Toggling this will allow you to spend 3% of your max mana on basic attack or skill use and add twice that mana spent as bonus damage. More burst to your Q.

4th Item, I like working towards a Joe Chills Revolver. This item is very expensive but well worth it end game to be a true assassin. it provides 70 AD and 25% crit chance and its passive is 50% bonus crit damage.  Wait, doesnt Catwomans Q provide on hit effects and act as a basic attack? HMMMMMM.  sounds good to me.

5th item, I like to grab a Batmans utility belt. Weve built all of our major burst items, were fed, and people are scared of you. Batmans utility belt is great for the 300 HP and the 15% CDR. But the best part about it is its passive. Allowing you to never be locked down (unless its a nightmare batman ult, then you just call.... worth. Seriously tho when are they going to nerf him...)

Last but not least item is truly situational and can be bought mid-lategame but if they are stacking armor it is wise to get an atomic axe to pierce through their resistance, and for an extra 500 gold compared to coda blade( which only provides +15 armor pen) you get an additional 20 AD. If they aren't buying armor, but they have an Ivy and gaslight batman is stacking soul of katana + Cheetahs claw get a coda blade to rip through that sustain.
 
Thank you for reading this guide. Leave your comments at the front desk, feel free to critisize as I do take it contructively. Stalkin.... Out.