Having another dog in your home would not guarantee better socialization.
My boys get along great, but Teddy has no tolerance for other dogs jumping on his head and doing other impolite things (in other words, acting like a rascally puppy like he does to his brother
)
I do not have experience with dog parks, but I would think that learning to socialize in a more controlled setting would be better. Starting off with one on one dog maybe? Or a training class with all the dogs on leash.
As Lola7133 wrote, basic training is also an essential element. Learning to follow your commands to come and sit and so on.