Be non-gender specific with your language - use terms like that person, our administrator, etc.
The term "guys" has become unisexual, while the term "gals" has fallen out of polite use.
Refer to positions in non-gender terms i.e. chairperson, business person, police officer, etc.
When you are aware of the gender identification of the position holder and they are comfortable with that being recognised then feel free to use such terms as chairwomen, chairmen, policewoman, policeman, etc.
Do not use terms of endearment with fellow workers of customers unless you have relationship with this person that makes such language permeable - avoid terms like honey, love, darl, sweetie, etc.