How do I know my construction contractor is doing a good job?

[Christopher Dunn]

I have no experience with construction or renovations but want to use the brrrr method. 

Especially if I want to close on a deal, I feel I dont have the time or ability to walk through a whole plan and pricing with a construction consultant to give me accurate numbers simply from an mls posting 

how does a beginner like me know:

if the contractor is doing a good job?

if he is ripping me off on pricing or quality of work?

what renovations make the best bang for the buck / what plans to lay out?

what the value of the house would be after renovations?

what house to choose that allows for renovations that add value?

How much the renovations are going to cost?