Whats the best way for a dog to get along with another dog?

Yes, make sure you don't dump the new dog in with the first dog at your house. It's HIS territory now. That's why he acts territorial.

Introduce them ON A LEASH. On NEUTRAL ground. By neutral, I mean like the park or something. No one's turf.

And try to socialize the anti-social dog you have now more. It can't hurt unless he's so agressive he'll kill someone.

It's not so much the breed that's important, as it is the individual dog that matters.

Introduce a new dog on neutral territory. Walk them together for awhile, and keep them apart, then slowly introduce - NOT face-to-face, but face-to-butt. Face-to-face introductions are a good way to start a fight.

Before you get a dog, you need to fix your current dogs issues first. If you bring in a new dog, you will have TWO "territorial" dogs, and double the trouble.

Go to your local shelter, and bring your dog, and pick the dog that best suits you, your lifestyle, your needs, and that best gets along with your dog.

***** You know what? What about fostering for a shelter or rescue? That would help your dog become accustomed to a new dog, without it being a permanent situation! You would help a dog in need, plus teach your dog how to live with another dog.

What I did with my dog was to get them used to each other before letting them be alone together. I first introduced them on leash, walked them around together and when they were comfortable enough with that I had them in dog kennels placed directly next to each other. One of my dogs was very territorial and would tip at my other one (even through the fence) but after a few weeks of slowly introducing new things to the two of them - such as feeding the calmer one first while giving attention to the other and vise versa - until they both got used to eating together. I also trained the more territorial one to share his food by feeding him then taking a handful of food while he's eating. This takes time too (I started out by feeding him and standing several feet away while he ate, worked toward eventually getting close enough to stand next to him while he ate, then eventually reaching down and taking a handful of his food while he was eating). Once the one dog trusted me with his food, I could then introduce the other dog to the area while the one was eating. Any training takes time, but just a couple minutes a day does the trick.

The best thing to do is introduce the old dog and the new dog on neutral ground. It may be a good idea to have them both on a leash at first, so they can't go after each other. Try to stay calm, because they can sense when you're nervous/anxious.

Take them for a walk together