Adopting another cat

I got a cat recently, in early march. I found him wandering in the wild, he was starving and on the brink of death. I saved him and he is now full of life and very happy. I started thinking about getting him a friend so he isnt alone all day. The thing is that im not sure how to go about that. He is about a year old, thats the vets best guess. He is a good boy just sometimes can be a handful but no bad blood here as we are still getting to know eachother, esp me as i never owned a cat before.

Ig im just wondering what all i should consider before i just get another one. Would a female or male be better, what age - a kitten or similar in age or much older cat, how do i even make sure my cat would accept the new one? So far whatever cat came to our window, he hissed at them. He also hissed at my aunts dog that is old and blind and didnt even do anything. He does just look at dog passing by our backyard with no reaction. Is it possible that he can be content with no other cat companion? I would like to give him the best life possible but im not so sure about risking it with a new cat and have that go sideways as i heard too many horror stories of how the old cat didnt accept the new one, they started spraying on things, became distant or aggressive towards the owner etc and i really dont want that to happen so any tips or your experience would be appreciated