When you use WhatsApp for work, it's important to follow certain protocol.
Do not wish your colleagues or bosses good morning every day on WhatsApp, without a purpose. Or Happy Sundays and such like. It is a nuisance.
Don't send inappropriate emojis to people you contact for work, who you don't know or don't know well enough. No hearts please. Or jokes and memes.
Don't begin with a 'hi' or a 'hello' or a greeting and leave it hanging, waiting for a response from the other party. Greet the person and immediately afterwards state your purpose.
Keep your message concise, clear and direct. Straightforward language is preferred over jargon or abbreviations when getting in touch with someone who you are not that familiar with. It should not be too casual either -- no yeah, lol etc.
Please don't send messages at inconvenient times, like late at night or early in the morning. Be mindful of the recipient's schedule and time zone.
Understand that busy people -- be they your seniors or someone you are contacting for work -- may take longer to respond to messages. Be patient and don't rush them for a reply. Allow them ample time to read and understand your message.