I am a primary caregiver and have had this role for 15 months. As a male, this does not come naturally, so I have to work at it. First, a caregiver must take care of themselves first, so they will burn out and not be able to help much. This means watching your own health, doing fun and interesting things outside of being caregiver for your mental and emotional health. Someone once told me it is like the heart, which pumps blood to itself first before it supplies the rest of the body -- so it can do its job. Also, you need to have someone you can talk with openly on a regular basis to relieve your emotions, frustrations, etc., for they are many on this journey. You can certainly vent here and get support, but it does not take the place of a one-on-one person you can talk with. I had to carve out a portion of my life that was "cancer free", where I did things just for relaxation and enjoyment -- kind of, mini vacations from the cancer scene.
Secondly, each cancer patient needs an advocate -- someone who will keep up with the scheduling, medications, appointments, etc. and battle the system to get the patient what they need. That often falls on the primary caregiver. The patient is often too tired, too sick to fight these battles by themselves.
If you have any specific questions of me, I'd be happy to answer. I never thought in my wildest dreams I could pull off being a primary caregiver on an ongoing basis, but with my faith I have been able to rise to the occasion. And maybe that is what these trials in our lives are about -- showing us we can rise to the occasion. Good luck.
Don