Ray Dalios book prinicples is a good place for you to start I would also get into if the numbers (financials) of the business. Basically being professional is about being dependable, reliable and delivering what you say you’ll deliver on time, to spec, without drama. Charge fairly and behave with integrity.
In terms of management lots of the Wharton stuff on coursera will help you there and the google project manager course is also very good