I cannot contribute anything other than editing. If you wrote:
The cat were a big one, and I saw he sitted on the tree and look mean at the small dog, who was braver than the cat who was scared.
I would edit:
The pompously large feline reclined in the elevated safety of his arboreal fortress. His stature dwarfed his canine pursuer whose ferocity would certainly have overtaken the cat had the cat not assumed a position that allowed him to look contemptuously at the now emasculated pup, whose uselessly unbridled zeal was now made a mockery off by the feline's alacrity to asylum.
Basically I biggify everything you say. Remember this is just an example, and should not be plagiarized and taken as your own, but as a guide to enlighten the scope of your vernacular.