Tracking is one of the main duties of a project manager, but deciding what to track and how is not always obvious.
1) First thing to know is that the level of detail of tracking is decided by the project manager. It’s up to you to decide if you want to track a project at work package level, activity level or task level.
You automatically decide at what level to track the project when you plan it. Think about it. If you put 1000 small tasks in a gantt chart then you will need to close them all.
In-practice: when you create the list of activities and you write them down one by one, ask yourself if you can track those activity and how? Will you be able to update them easily with a percentage of completion? e.g. 0%, 50% 100%?
2) You also need to decide how you are going to mark the completion of the activities in the gantt. There are few different ways to do that. You can have 0-50-100 progression. 0-10-50-100 or ask your team members to tell you the precise the status (this last method is often less reliable).
I personally believe that is not effective to put an exact status based on feedback e.g. 72% unless you are tracking a project that allows to do so: installing a new software on a 100 machines.