I strongly encourage EVERYONE on this site with PTSD who can properly care for a Service Dog (SD) to get one. SD's can help with a lot of other conditions like anxiety, depression, etc. SD's can also serve as emotional therapy dogs - providing emotional support as well as the tasks they are trained for in relation to your disabilities. It's not just one or the other. Having a Service Dog in Training (SDiT) for me has allowed me to start to reintegrate into society. Baby steps, but it's progress at least, where before, I was in just a state of stagnation.
To see what a service dog can do, which is a lot, Google or youtube the words "PTSD service dog". Lots of videos, most are good, some... not so much.
A SD will be with you almost 24/7/365. The best way is to get one already trained in my opinion. The waiting list can take a long time. If getting a dog already trained is not an option due to the cost, some organizations will donate fully trained dogs. Some people/communities hold fundraisers to come up with the money for a trained dog.
If getting a fully trained dog is still not an option, you can train your own if you have the patience. It's not an option to take lightly. Most people who try to train their own, fail at some point. Sometimes it's the dog. Sometimes it's the owner/trainer. Sometimes, it's a combination of factors. I'd like to think I'm doing well at this point in my dogs training. I know I could be doing better, it's not a race or competition though. It takes a tremendous amount of patience and a lot of time. Patience is not a quality I've been known for since PTSD set in. I'm not trying to discourage anyone, by any means. Just read my opening sentence of this post. I'm just trying to make sure whoever is considering training their own dog takes the commitment seriously.
Some states are SDiT freindly. Some are not. This is another factor to consider if you want to train your own SD.