On pet-keeping

As we all know, pets are people's friends or the members of their homes. They are lovely and clever. Hut why are so many people keeping pets? Maybe they really love the pets. Maybe they like to name their pets and train them. It may show that they are friendly and caring totheir pets. Some bad pet owners discard them when they feel bored with the pets, so the pets have no choice but to become homeless pets.
It is the homeless pets that are harmful to the society. They may have disease to transmit to people , and they may hurt someone while they frightened. They make noise at night to disturb people's dreams. They breed a number of baby pets, hence, more and more homeless pets will exist in the society.
So for my part, if you want to keep pets, you must take into account clearly. Don't let them be just a whim.

[Very good.  You just have to remember to capitalize at the beginning of sentences and leave a space after all commas and periods.]

on pet-keeping

As we all know, pets are people's friends or the members of their homes. They are lovely and clever. But why are so many people keeping pets? Maybe they really love the pets? Maybe they like to name their pets and train them. It may show that they are friendly and caring to their pets. Some bad pet owners discard them when they feel bored about the pets. So the pets have no other choice but to become homeless pets.

It is the homeless pets that are harmful to the society. They may have disease that transmit to people. They may hurt someone when they are frightened. They make noise at night which disturbs people's dreams. They breed have a number of babies pets, hence more and more homeless pets will exist in the society. So for my part (not sure what you mean by 'for my part' in this context),if you want to keep pets, you must take all this into account clearly. Don't be just buy a pet on a whim.

Hope this helps. Feedback on how to improve my corrections is much appreciated! 

Alex