Lately there are more and more cases of account theft.
This is what I do to be sure:
For starters, using Vessel to make transfers is the best option. It is a wallet that made 
Vessel . Here put only the active key when you import your account.
Post presentation wallet vessel
Just login in steemit with the posting key in the browser you use. Absolutely never login with the owner key.
Change the owner key and store it only on physical paper and perhaps in an encrypted app. Although I personally opted for the physical option.
Never send keys neither by email, nor by wasap, nor by telegram.
Never open links that arrive in the story in the wallet and suspicious links in the comments either. I never open a link sent to me in the wallet or in a comment.
With these tips it is really difficult for an account theft to occur.
Greetings and steem on!