I already got accepted to a university for an MS program but I don’t know squad about PhD programs and might opt to skip the master and apply somewhere else for a PhD, what are the things I must know about a PhD program, how hard is it to get accepted.
My degree is Physics. Will I need the GRE and work experience? what are the things I should focus on now before attempting to apply?
Yes and no, respectively. The GRE is normally required for the application, work experience is generally of little value unless it is heavily research-based, preferably supervised by a PhD.
Research.
Do you want a career as a researcher, and/or a university professor? What are your career goals?
If you are trying to start Fall 2017, the deadlines for virtually all programs will have passed already - you’d have to focus on admission for Fall 2018.
The difficulty of admission varies by program, but overall it’s pretty difficult to get selected into a good PhD program. The application pools tend to be self-selecting (e.g., you will be competing with the top students at great schools) and even then acceptance rates can be lowish to low.