I know little of the formalities associated with sources, but I want to be as accurate and in conformity with the rules as possible. I use FTM 2017 and am stuck at selection of the proper source template. I would start with Cemetery Records, category Derivatives. But the obvious template associated with Find A Grave would be Online Database does not seem appropriate. This index appears to be based on the name of compiler being an individual. My first thought would be to enter Find A Grave on that line, but came across this cite and decided to find out what the experts think.
Depending on what exactly you are citing Find A Grave for, I would opt for the suggestion made on Randy Seaver's blog here. I'm not sure if the source templates in FTM 2017 and RootsMagic 7 differ in any way, but Seaver suggests using the "Cemetery Records, Compiled (online databases)" template. I'm sure there is a similar template available in your software of choice. Evidence Explained also has a QuickCheck model for online images taken from sites like Find A Grave, if you choose to write your own freeform citation.
However, I would urge caution in citing Find A Grave generally (unless it is for the attached gravestone photograph). The vital data can be entered by anyone and does not allow for sources to be attached. Try to confirm the details for yourself from available records, and do not take it at face value. At the very least, you should be consulting other (preferably primary) sources to support your conclusions.