Find a few online CNA certification courses, such as those found at the Nursing Assistant Guides website. These courses should be certified by the National League for Nursing Accredited Commission (NLNAC). Weed out the online CNA programs that do not meet this accreditation standard. You will have a difficult time transferring your course hours to a higher education institution later if your program is not certified.
Talk to other students on CNA forums online. Find out their experiences, and see if any of the schools you are considering turned out to be scams, or if other students' experiences with them were less than ideal.
Complete your clinical practice. According to the Nursing Assistant Guides website, the majority of accredited online CNA courses require you to work in a clinical setting to learn what you need to be a successful CNA.
Register for and take your state's CNA certification exam.