Ask the DGS for the names of currently enrolled students to whom you could speak. 1722 N Street NW, Washington, DC 20036 has many publications that will be of use to you. G. Faculty who have graduated from a particular institution. Find this information in the Barnard and Columbia catalogs. It takes a long time.
Confidence is important and easy to lose hold of, so a support network is important.
Developing writing and researching skills is the most important part. You learn more than you ever thought possible. Do really well your first semester. Make your fellow students into colleagues. Don't aim to make your dissertation your seminal work.