There is no obligation to approve every friend/connection request sent your way. A good rule to try and stick to is to avoid approving requests from people you have not met at least once in real life.
Be mindful of who you add from work. There is nothing wrong with keeping your social media life separate from your work life. The degree to which you do or do not connect with coworkers online is a personal choice that should be respected. If you do blur the lines, be cautious of what you share.
The easiest way to deal with negative comments, from a friend or stranger, is to simply not respond. If you do feel a response is necessary, take time to think about what you will say. You may find that with time a response really isn’t necessary. If you do write a response give it a proofread, ask a trusted confidant for feedback, and/or read it aloud before hitting “submit”.
Only post photos you wouldn’t mind potentially anyone seeing and extend this courtesy to others that may appear in your photos. It is OK to ask a friend to take a photo down. A good first step is to untag yourself if you are in the photo, and then send a polite message asking that the photo be removed.
Stay away from vague statements and be cautious when complaining. Be mindful of the amount of information you are sharing through your updates. Are you oversharing? Posting too frequently? Before updating your status ask yourself if this is really something you need to share.
Not everyone wishes to be tagged in pictures, but it is near impossible not to show up on Facebook at least in the background of a party or event. A good rule of thumb is to not tag people in photos unless you are very confident they would want to be tagged. People that want to be seen in a photo will tag themselves. You can set your privacy settings to alert you whenever you are tagged. This way, you can approve or deny tags from other users.