Put A Leash On
I think the number on piece of advice I can give to any dog owner who is having any kind of problem with their dog is, clip on that leash! With a leash on, you have direct access to your dog. If your dog gets rowdy when people come in the door, you can grab their leash before opening the door and instantly begin working with them on how to not jump on that person or run out the door. If your dog likes to run and hide under something when they get an object in their mouth that they shouldn't have, with a leash on, you can take that leash and immediately being directing them out of that hiding spot and initiate a Drop command. If your dog has a hard time settling down when you are eating a meal, you can help them understand how to hang out by your side by putting their leash under your foot and giving them just enough room to sit and eventually lie down comfortably.
Think of the leash as a USB cord. You are the keyboard and your dog is the computer. Whatever you say, travels through the leash, and your dog receives that message and acts accordingly. When there is a communication disconnect between you and your dog, then the simplest most effective thing you can do is reboot and reconnect using the leash. In the dog world, the quicker they understand how not to do something, and the more meaningful your follow through, the quicker they act to do what it is you want them to do. Having a leash readily available allows you to act quickly and set limits. The more limits a dogs has, the less options they have available to them. The less options, the less they are capable of escalating in behavior. If they are not able to escalate, then they only have one other option, to calm down and look to you for the next directive. It really is that simple! Putting that leash back on your dog is the first proactive step you can make in improving your relationship with your dog. When your dog fully understands your expectations of them, they are more than happy to fully comply!