@breatheme For me my first hard lesson was don't assume people who work with dogs have the same level of professional training I have to have in my own field...
I let my dog down badly because I trusted a dog professional knew what they were doing. I should have been a lot more picky on what actually are your qualifications and been a better advocate for my dog. I let it happen for too long and his frustration reactivity was not helped by it.
Second would be to not apologise too much. I was terrible apologiser and took everything so much to heart! My dog trainer was very pragmatic and said seriously most dogs have reactivity in their own specific context. One day I felt that and heck we are not a unique and rare club at all... but other care less about their dog behaviour!
It was very freeing to apologise less and know as long as I was trying/ thinking safety/ doing my training I was actually a good owner!
Third and most important was that while trianing is important it is not as important as shaping his brain through enrichment and play and just having fun. My break through was going at his life and routine and maximising his quality of life and enrichment opportunities and then him an I just oh playing games doing drills and agility tricks and having fun so we could praise and bond. Yes they were "lessons" but it was stealth learning and fun for us both so no anxiety and pressure attached. A definite tip this one!
Can I add a few more.. pretty please?
Manage the environment to set up the dog for success and gradually behaviour adjust: vital!
Sniffy walks and chilling in green space
Dogs don't need a human life. Don't envy other people out shopping etc with their dog. None of that is for the dog and many are stressed. You are as good an owner and having as much fun taking your dog places it can mangage and be happy in even if that's chilling and snuggling on the sofa!
Lastly the whole world has opinions and they are like AHoles... don't discuss or let other comment on your dog and training (well forums like this being supportive excepted lol!). You know what you are doing and most people have no clue about dog training. I just uhuh and mmhmmmm and walk away. I wish I had known that at the beginning. It would have saved me from peoples opinions beating me up!
On the other hand a good behaviour level trainer who can give you confidence and experience is gold dust and worth any money
OK.. too many tips but... :-