You can use any painting medium to do the Virtual Art Academy® Apprentice Program: oils, acrylics, watercolors, pastels, and even digital media, or photography. Because I teach the underlying principles that apply to all artwork, the course applies equally to all media.
If you are looking for the easiest medium, there is not much to beat oils. You can read a full discussion in this article on how to choose a medium for painting.
You can also download the attached eBook for a list of materials & supplies you will need to get you started.