Where is the best place to start to become a caregiver?

I'm glad to hear that you had a relationship with your grandmother. So many caregivers have that soft spot for a grandparent. That inspiration might be more important than the offical steps to becoming a professional helper.

To start you might try getting a job at a home care agency. Many provide training. You might start out as a companion. As a companion, you need to know how to give personal care, how to transfer an elder from bed to wheelchair to bathroom. Even though you might not work as a nursing assistant, you might want to take a CNA course. Becoming a liscensed CNA will give you flexibility. The most important skills are listening and appreciation.
Appreciate that everything in the elder's world is precious. Treat possessions as sacred. Learn his routines and appreciate the comfort they bring. Learn how to slow down when you enter the older person's world.
As a professional caregiver, you will need marketing skills. Make a list of all your skills. Do you cook, garden, shop, sew, play board games, drive. List all the things you are good at and like to do. Make yourself a card with a picture of yourself along with phone and email. Or make a brochure that tells the services that you offer. Some people, these days, use Facebook or other social networking. Tell everyone you know that you are looking for caregiving work. Put up cards on bulletin boards at churches, grocery stores. Make an appointment with the Area Agency on Agency. Tell them of your interest. Put cards at senior centers. Answer ads. I wish you luck on your caregiving path. I hope you will soon find someone to help.