A common answer is "Take privates from professional(s)". I agree with that. Pros can tell you what you need to hear now. And if you are receptive enough and do what they tell you to do, their advice can help taking you to another level. They are there at your service.
But if you want to take a shorter cut and save some money on the lesson fee, learn the notion of the Diagnostic mode, and how the Pros think at the beginning of a private session.
First of all, I consider taking privates as an equivalent of visiting a Doctor. But too many patients/students show up without knowing what's wrong with them, or what they want from the session. They have a vague sense of "My dance needs to be fixed", but are not sure what to do.
Unlike other teachers, dance teachers need to take care of very diverse levels of students. It's like he has to figure out whether the student is at elementary school level, high school level or graduate school level, then start teaching. On-spot assessment and diagnostic is an essential skill for them.
You have to be careful about giving dance advice. Good advice for an advanced dancer may not make sense to a beginning student, and vice versa. Value of advice depends heavily on the student's level. Another reason for the importance of diagnostic skills for dance teachers.
From the Doctor/Pro's standpoint, if the patient/student has something specific, a well defined question or request, it's much easier to work on it. The Doc/Pro is there to help. But he needs clues.
Let's say, a couple shows up, saying, "We'll do WCS strictly swing comp for novice category next month. And we want to do well."
This is a clue. From this, a Doctor/Pro would think, "Strictly means they are a dance couple, and signing up together. I got to see them dance, diagnose some points that may work as their strength and weakness in competition, and provide advice for changing them. Then I'd add some tips or moves that they could use to appeal to judges. "Next month" should be a long enough time to work even on very basic body usage, and that's good."
This initial thinking determines how the session would go. He'd ask the dancers to dance a song or two, and start diagnosing the dance.
His answer can vary depending on what is requested. If the comp is tomorrow instead of next month, it may not be very fruitful to ask them to change basic body usage or something that cannot be fixed overnight. So he may only say it briefly or may not mention it at all, and may focus on something fixable overnight. What judges would seek for novice are different from those for intermediate/advanced, and his advice would reflect that too.
Just like a family doctor, if he knows the patient/student for a longer time, he can provide service for longer term in mind and with better accuracy.
If you do not provide clues, an option for the Pro is to be a taskmaster. He'd ask you to do some moves, and would start correcting them. That should work, too.
In general, dance advice can be one of the following;
About Body (genetics)
About Body (usage)
About Knowledge for the dance (or lack of, or about misconception); what to do and how to do
About Particular skills and drills
About Mental attitude (or lack of, or about misconception)
For a blog entry that is meant to be short, I'll save the details. But when you take your privates next time, give it a thought about how you can interact better with the pro and get more out of the session.
In short, learn to be a better learner and a good student. It can be your shortcut for better dancing.
For Pro vs Pro interaction, this is not always true. It's more like Doctor and Doctor interaction, with mutual respect for each other's specialty and ability.
[You better give good clues for your Pros/Doctors]
