Step One: Find a well-known/donor rank seller! Do NOT trust 90% of the citizen rank sellers because most of them would scam. Why would they buy a rank for you when they don't have a rank themselves?
Step Two: Be sure the price is REASONABLE. If they want to sell you a rank for 1k, then most likely it's a scam for you.
Step Three: Quite possibly the most important and an important fall-back plan. Take screenshots. If all else fails and you are scammed by even a donor, then you can get your money back by a staff member and get the scammer banned for the rest of the community.
To take screenshots: ( Windows )
Hit F2 on your keyboard (If it does not give you a message in chat such as Saved Screenshot as (#'s) then most likely you should hit Function (FN) and F2.
Next, go to your search bar and look up %appdata%
Click on the .minecraft file
Click on Screenshots
Choose the screenshot you took.
To upload it:
Simply click Upload A File, then choose the screenshot using the steps above
Meepcraft is a fun place, we don't need scammers.