Dog training classes (for non-specialty dogs) are almost entirely about training the human to be consistent.
My experience (dog count of one as an adult, after reading a dozen training books and doing two dog basic obedience courses [about 8 sessions each]) matches that. Our dog knows what she can get away with with different family members and I’ve inadvertently taught her to “politely beg” for snacks in certain circumstances that I will try not to repeat for any later dogs.
Make them feel secure, be consistent, be wary of over-treating and being too varied in training. “Come”, “Comehere”, “Get over here” might as well be three different commands. One trainer said dogs don’t generalize well. They might quickly learn “when he says that and I’m in the kitchen and he’s holding a bowl, I should sit” much faster than “when he says that and we’re outside and a squirrel is running around, I should sit” much faster than “anytime he says that, I should sit”. (It’s really fun watching them puzzle it out and I could tell when my dog was really trying vs just being disengaged.)
What would I do the same: crate train. love my dog and make her feel protected and provided for. Do basic obedience training. Lots of short training sessions. 10 3-minute sessions a day is not wrong. 1 hour-long session is. Ensure that if she ignores a command she knows that I consistently enforce that what I want happens. (If she ignores a come command for example, I will always march to her and make her come to where I was standing when I issued it. My spouse does not [despite being overall more consistent]. Our dog knows this and acts accordingly.)
What would I do differently? Fewer treats during non-training times. Teach the kids to give the same consistent commands. (Dog pre-dates kids in our house, so this was not possible.)
Our dog is 15 pounds and we decided to let her on the furniture (inc bed) and we’d do that again for a dog under 20 pounds. With a larger dog, don’t let the puppy dog on the furniture if you don’t want the adult dog on it.
100% agree on the suggestion to pre-determine dog ownership and not have it be 50/50, we’ll figure it out, YOLO.
I would 100% crate train. The amount of consistency it provides helps incredibly, not just for potty-training (but it’s incredibly helpful for that, of course). It’s not doggy jail (unless you use it to punish, in which case just don’t get a dog). Our dog would happily go to her crate when overwhelmed by kid visitors and though we later took the crate away, we put the same little padded mats in several spots around the house for her, including one in a closet that she likes to use while we’re working or during thunderstorms.
I hesitate to recommend specific books as I read a stack of them and probably got something from all of the first four or five.