In my opinion, experience is the best way to get better. That said being able to bounce ideas off of a more experienced player helps close that gap faster.

When I was picking up Roaming soldier, I found a mentor to watch demos with me. Everything else I did was through experience inside of TF2 and watching POVs of other players and streams of those roamers in their match. If you have a friend who is on a 6's team, try to ask him/her if they can let you sit in on a couple scrims so you would have a feel for what the comms are like for the class you want to get better at.

:>

It speeds things up, and you can get a leg up and a head start on the people who came before you. There's a reason we have coaches, teacher, professors, text books and mentors in life. To learn from someone(s) who already put in the work.

When we hire someone at work we don't set them loose, we give them a mentor. We invest in mentoring enough that we even have a billable code to bill time for mentoring a new engineer. We don't have time to wait around for them to try to learn everything on their own, we have clients waiting.

i think mentors can help tremendously. for example, you could be watching a demo of yourself on your own and realize all these mistakes you made, but can only figure out what you could have done better for a couple of them. i mean you can try to see if someone will take their time to answer your questions, but having a solid mentor until you don't need one never hurts.

Mentors are valuable in helping identify mistakes that inexperienced players might not recognize on their own. You can tell when you were in a bad position or when your team made a bad push, but you might have trouble understanding what could have changed that. And unless you experienced it hundreds of times you might not know the solution. Even if you know the issue and understand the solution, its nice to have someone who can tell you that you're right. Talking with your team about it for ideas is often good enough.

My mentor is now my teammate. I still make mistakes, and I'm usually quick to recognize and understand them, but I feel much more confident in my play knowing I'm surrounded by more experienced players who are there to help.