I found out about being the alpha by accident when I saw my neighbor's german shepard running loose. Since I knew the dog I put my infant on my hip, grabbed the dog's collar and took him to his house. Only to discover her dog was home. So I read the tag and walked the dog to his real home - a house with a fence that was over my head. The owner came out amazed that I had his 'aggressive' dog under control. Today I am more careful with strange dogs than I was. I'm not willing to take the chance.
Since then I have just assumed the alpha position with my dogs and it works.