If I am looking for a dog trainer, there are few questions that I want them to answer.
1. What happens when the dog gets it right?
2. What happens when the dog gets it wrong?
3. What kind of equipment is employed and recommended to pet owners?
5. How do they identify fear, anxiety or stress during training?
6. Are training results guaranteed?
These are reasonable, but tough questions to answer! I thought I'd take a stab at them from my perspective...
1. It depends on what phase of training we're in. Initially, when learning new behaviors, a treat or some treats and praise.
As training progresses and ques are loaded and learned, I will often just use a marker and keep going with additional commands/tasks, a process known as chaining.
I also use toys as a reward in various scenarios as a reward. Toys tend to excite puppies/dogs a bit more, so I only use them when a higher excitement level is appropriate.
2. Again, it varies. Initially I ignore failed attempts. But I use a marker too, to let the dog know that they didn't quite get it right - "nope" is what I use. I then encourage them to try again. Again, as time and training advances, expectations increase too. But markers help to communicate the results.
3. My personal preference is none at all! No collar, no leash, no nothing! Of course that's not always possible, given leash laws etc., but I'm a HUGE promoter of doing most foundational training at home and without restriction of any kind whenever possible.
If leash and collar must be used, I recommend a flat collar or a Martengale collar.
5. Fear, anxiety, and stress during training is identified the same way as when not training, eyes, body language, posture, lip licking and/or excessive yawning etc.
If one's training is causing any of these signs it's time to step back and reevaluate the approach!
I like to view training as structured play. It doesn't need to be a set - and often - all-too-serious formal session. It should be fun and engaging and lighthearted. Everything you do with your dog IS training, because they are always learning!
6. This is the toughest question here IMHO! I can guaranty progress! But each dog will be different in the result achieved based on breed, genetics, previous training, habitual issues etc. So yeah, progress yes, end result after x amount of work, no.