The concept of sounding and looking businesslike seems as though it would be appropriate for a business setting. Unfortunately, it nearly always translates to an unfriendly facial expression and a disinterested, bored or angry tone of voice.
Test it by looking in a mirror with a “businesslike” expression. See how robotic and cold you look? Hostile, even? Practice a phrase with what you consider to be a businesslike tone. Can you hear how curt and unwelcoming you sound? When there is no welcome in your voice, it doesn’t matter what the words are, you sound unpleasant.
Now, test yourself by smiling (not a grinning, just smiling) and asking, with a friendly tone, “How can I help you today?” Smile while saying, “I’m happy to be asked questions and I’ll also be happy to answer them.”
Whatever you say, say it with a sound that is encouraging and pleased to be asked for help, not discouraging and irritated that you’re being bothered. You will feel differently and sound differently. You will certainly make a better first–and lasting–impression. (This applies to your internal customers at work as well!)