When you start a new project, figure out what tasks in that project will require help from other people. Make your first priority be contacting those people and getting them to do their part in it.
It's very, very tempting to leave the part that requires others for later. Resist this temptation. If you run low on time, you can push yourself to get more done. You can work harder or stay late to finish what you need to. It isn't fair to expect others to do so because you waited, and they might not be willing or able.