How to Set Your Tone
Stick to being clear, concise, and most importantly, human. Remember, these messaging platforms are here to cut down on emails, and improve project management on the fly. At least, that's their primary purpose. Inviting peer-to-peer conversations is a sometimes healthy side effect, and the cumulative effect of your chat practices amount to a definitive aspect of your company's culture—but we'll get to that later.
The best way to find your tone is to imagine having that conversation face to face. What I mean by this, is that you wouldn't send your boss the same venting message you'd send your work spouse. But you shouldn't be sending bot-like messages such as: "Dear Chris, per my last message, I wanted to confirm..." either.
Try typing out your message, and reading it back to yourself as though someone else had sent it to you. Does it feel natural, while also passing for professional? If it’s casual, have you established that level of rapport with the person you intend to send it to? By putting yourself in the recipient’s shoes, it’s easier to filter out what might be perceived as over the top or disingenuous.
Let's Talk About Words
In the world of instant messaging, there is no body language or context to minimize the effects of using the wrong words... Sarcasm in chat? It’s almost guaranteed that not everyone in the channel will pick up on it. Being known for having a great sense of humor is one thing, but generally not when it comes to executing on important projects. Ask yourself if jokes or insinuations are worth it in chat, or if you might be better off saving that candidness for in-person interactions when people can better read your body language.
That goes for jargon or slang, too. Trust me. People will interpret it in all the ways that you didn't intend. That doesn’t mean you should avoid using culturally specific references, but if you do, be prepared to explain what you mean in no uncertain terms.
Finally, speaking of words—check your work. While you're not writing an essay, and you're most definitely not Hemingway, whatever you send should demonstrate intention. Don't send your spell-checker into overdrive mode or anything, but do scan important messages for spelling mistakes and to ensure that your message is clear.
The GIFs Dilemma
To be honest, I've lost count of how many GIFs I've sent via Slack while at work. They. Are. Precious. And you can not take them away from me. Indeed, those precious, animated images are so ingrained in how we communicate, that Slack even has a shortcut to auto-generate a GIF based on a quick word search.
But sending a GIF to someone at work can be tricky business. Often, these little snippets are associated with a cultural reference, a TV show, pop-culture phenomena, or the latest viral meme. By default, that immediately should narrow your pool of possible recipients for a GIF, as you need confidence that all recipients will understand the true meaning of your message.
Know your peeps. For example, my boss and I are die-hard fans of The Office. Consequently, whenever any of us make a comment that brings to mind a punchline from the show, we both know to expect a GIF. But that still doesn’t mean my boss can send me the "that's what she said" GIF. Remember, just because they’re GIFs, doesn’t mean they can’t offend.