Introducing a new kitten to a household?

[Brittainy]

My husband asked me about bringing home a second cat. The cat we already have is a 7 month old Siamese cat. Up until recently John, had a companion Chihuahua (my sister in law's) and the animals were never left alone for more than a hour or two.

At the same time my sister in law and the dog moved out, I started working full time. For the last few weeks, John has been alone at least 5 hours a day during the week and he is not too happy about that. He is starting to get more aggressive and destructive. This started right after dog left, but I realize it could be that he has not been neutered yet. John is completely an indoor pet and we plan on neutering him after the holidays. We think another cat might help with the recent behavioral problems because we know most Siamese cats do not like to be alone.

The new cat we are considering is a little over a year old, neutered and the owner had him de-clawed. He is from a household with other cats that were much older than him. The problem the owner is having is that the kitten plays too roughly for the older cats.

I haven't decided 100% on getting the new cat. If we choose to do this what would be the best way to introduce them to each other?
Our current cat has claw in tact still. The new cat is over a year old, Our cat is 7 months.