I had a schnauzer that I trained myself after taking a previous dog to obedience classes. I started with stay when she was only 10 weeks old--mainly to make her stay in her bed while we ate dinner. It took a thousand trips to take her back to her "stay" place, but she got to be very good at it. We lived on a street with curbs, and I even taught her not to go across the curbs into the street. Mainly, whenever she got close to it, i would watch her and make her stay. Eventually, she would not even chase a ball that rolled into the street.
This was a big safety thing because our previous dog had gotten killed at a young age when she ran into traffic. I did not want it to happen again.
One thing I did was to combine with voice signals were hand signals. Holding my hand flat and closed while pointing it at her was combined with "stay" for example.
The best thing I taught her, though I don't remember how, was to spit something out. One day, she leaped up at a low-flying bird and caught it in her mouth. I yelled spit it out, and she did. Bird flew away unharmed!