In The Name of Allaah, The Most Merciful, The Bestower of Mercy
Answer: It depends on what the situation requires, but your habit should be that you show a friendly [or welcoming face], for this is the best thing by way of which the people will be attracted to you, have love for you and approach you with their confidential affairs [i.e. to seek advice]. But if you are misrable [unfriendly or unwelcoming], the people will fear you and will be unable to speak to you.
Sharh Hilyati Taalibil Ilm’ page 52. abridged & slightly paraphrased