Steemit Utilizes Many Permission Keys/Passwords
The most obvious and most important security measure to remember is obviously your Master Password. Never give it out, try to use it as little as possible, and of course secure it as you would any vault key.
One way to better do that is to use some of the other keys for the functions that don't require all the access. For example, when only posting try to only use your posting key as your login. This prevents you from... oh I don't know, accidentally pasting your master key into a post or something crazy like that.
I'm not going to go into full detail over this and would rather reference this old article to consider:
https://steemit.com/steemit-guides/@pfunk/a-user-s-guide-to-the-different-steem-keys-or-passwords
One thing I am going to do is show you this table made from that article referenced above:
How do you find your keys? Just go to your wallet and look for the sub-menu labled "permissions" near the mid/top left side. To change your master password at any time, obviously click on the "password" sub-menu.