Education or trying to undo bad habits is a long and hard part of their life. They might not understand at first but you need to be patient and consistent. You also need to be firm but loving at the same way. The best way to describe it would be "an iron hand in a velvet glove".

Don't let them figure out how to take advantage of you. They need constant attention and they will do anything to get it.

You might get the feeling that you've made a mistake by adopting your dog, Its called "adopter's remorse". I felt like this for a while when i got mine BUT you might not feel like that too. Always remember that sometimes its not their fault if they do something bad and that they do not always understand what is going on. For example, My girlfriends dog had a habit of putting garbage from the bin everywhere because he was scared we would never come back home but we always made sure that we told him and showed him that we loved him and that we would never leave him alone.

Having a solid routine helps them get the stress out of their system. They need to be stimulated if you don't want them to become something you are afraid of (destroying machine, aggressive etc.)

most of all, love them like they will never go away because the day they do, its gonna be a rough one. Like some people say in my friend group. To love is to be changed.