...and then wait for me to reply.
It's like calling someone on the phone, saying "Hi!" and then putting them on hold.
When you do this, you make the co-worker wait while you phrase your question, which loses productivity and disrupts focus.
Instead, phrase your greeting and your issue all in one single, complete message:
This allows the recipient to process the request immediately, answer when they hit a natural breaking point, or pass along the answer right away if they're online.
Similar behaviors to avoid include:
Just ask the question!