Originally Posted by Venedicae
I don't know why. Is there a way to fix this? Manamune? Stop using too much abilities?
Stop using abilities. I never have mana issues with Caitlyn. There are really only a couple of times you should be using her abilities.
Q - Only use when you have a guaranteed clear shot, like if Taric stuns your opponent and there aren't a bunch of minions in the way.
W - Keep 3 up in bushes or zoning the lane.
E - Only use to escape or gap-close to secure a kill.
R - Obviously only use when it's necessary.
If I were to guess I'd say you're trying to spam Q too much. This is a common mistake with inexperienced Cait players. Remember, your Auto-attack range is better than any other ADC early in the game. Use this to harass instead of your Q. Only use Q to lay down a solid chunk of damage when it's DEFINITELY going to hit. (as mentioned above)
Don't ever buy Manamune on Cait. Sivir, Ezreal, or Corki maybe. .But never on Cait.
boots + 3pots
Then build Infinity Edge, Phantom Dancer.. Follow with
Blood Thirster if you're doing really well and farming a lot.
Guardian Angel if you have died even once during Mid-game.
Last Whisper if 1-2 enemies have over 150 armor.