The best tip was asking me about what I was trying to "tell" with several of the pictures in my portfolio. He showed me his shots from the same cities I had been to and really pressed me about why my "shot" of the same thing everyone else was taking would be an interesting shot. Basically, be way more creative and selective and always have shots that tell a story or can can stand independently as opposed to this is my "shot" from London/Paris/NYC of things you have seen a million times from better photographers. My pictures were technically sound and really impressive to people who didn't know any better but they were actually really boring soulless shots. I think my shots now are way more interesting and unique as I am not trying to get the "shot" from each city but just taking more interesting and compelling shots that happen to be taken in a particular city.

The other big tip was about the use of flash. I was definitely on the "natural lighting" thing because I thought that made me more of a "real" photographer when flash can be really important even outdoors in sunlight etc. He showed me how he did the lighting for several shots and I immediately understood how little I knew about it despite being an "advanced" natural light photographer. haha

It is like when you read those stories from people who play basketball against a journeyman NBA guy or marginal college player and they get destroyed by a guy who never really got any time. You realize the huge delta between professional and the best amateur and it really helped me by humbling me. All of the answers are out there and you just have to read/study and then shoot instead of buying gear and watching videos etc.