One of the most effective steps you can take to protect your cloud account is to make sure you are using two-step verification. In addition, always be sure you know exactly whom you are sharing files with. It is very easy to accidently share your files with the entire Internet when you think you are only sharing them with specific individuals.
To learn more, check out this OUCH! newsletter: https://securingthehuman.sans.org/newsletters/ouch/issues/OUCH-201611_en.pdf
More cybersecurity education available here: https://prezi.com/zkrdursavbgu/