I watched a special about service dogs in the past. This documentary showed these service dogs were all Black Labrador Retrievers. It took a certain (long) length of time to train them to know what to do. The person in this documentary I believe was on a list to get one. There are a number of other details to tell You, but this message would end up being much longer. Call the Epilepsy Foundation to get more and better information from them/possibility the documentary.

there are a few places that have signs up that only registered service animals

You would need to go to a professional dog trainer. Your dog will need to be completely unreactive to people, other animals and any kind of distractions.
How would you want your dog to help you? Bring a phone or your medicine to you?
Many people were buying service vests and fake credentials off of the Internet and calling their pets "service animals", which has led to numerous bad accidents.
I believe the current laws are that airlines, buses, stores, restaurants etc. have to let you bring your service animal with you but you do have to provide proper paperwork of up-to-date shots etc.
Sadly, people abused this by slapping a service vest on their untrained animal, leading to biting accidents and other problems on airplanes, restaurants etc. Some person tried to bring a Turkey or a Peacock on a plane, calling it his "service animal." Other people have called their mini-horses or pigs service animals.
That sounds ridiculous to me and has really hurt the true service animal industry.
So, I think the laws will soon get stricter and people will have to prove that their animal can really perform in case of an emergency.
Of course, it's obvious when a blind person has a service dog that there's a real need for it, but those dogs are HIGHLY trained and very expensive.
So, think about what kind of aid you require from your dog and find a trainer that can help you.
Good luck!

I just watched a documentary about service dogs, the dogs that were being trained and the ones people had were black Labrador Retrievers. They are smart and kind animals. I know a person that is blind and the last time I saw that person I believe it was a German Shepherd next to that person.

any dog can be a service dog. i think the qualifications is ... mastering the basic training, special training, your dog need to get used to people and animals and noises, and you have to spay or neuter your animal. i know there is more but my dog doesnt like hyper dogs and a couple of neighborhood dogs are mean and/or hyper.