A studio portrait is the one session where the clothes do more work than the location, because there is no location — there is a background, a light and you. Bring two or three plain tops in solid mid-tones, plus whatever you actually wear to work rather than what you think a portrait calls for. Fine stripes and small checks interfere with the sensor and shimmer on screen, and no amount of retouching removes it afterwards.
The session runs half an hour, which is enough for one lighting set-up and two backgrounds without anyone getting tired of their own face. The selection is made together at the end rather than sent as a contact sheet a week later: you see what there is while you still remember how each frame felt, which produces a better choice than looking at a hundred thumbnails on a Tuesday. Twenty-five retouched photographs, delivered to your gallery within 48 to 72 hours of the appointment.
A few small things matter more than the outfit. Have a haircut a week beforehand rather than the day before, so it has settled. If you wear glasses, bring the pair you wear every day; reflections in the lenses are dealt with by moving the light, not by retouching later. Make-up can look the way it does on an ordinary working day, with a little powder against shine on the forehead and nose. And anything bought specially for the photoshoot has a habit of looking exactly like that in the frame.
Say what the photographs are for when you enquire. A portrait for yourself or your own profile counts as private use, which you may share and print as you like. If a frame is going into a press kit, onto a book jacket or into an advertisement, that purpose is named in the written confirmation so the rights of use match it. The rest is short: fill in the form, receive a fixed price by phone or email, confirm the date in writing. There is no deposit for asking, and the price does not move once it is agreed.