Start with a thorough cleanse
Remove buildup without scratching or aggressively manipulating the scalp. Condition, detangle in sections and rinse fully.
Dry completely
Unless a wash service is confirmed, arrive with hair completely dry. Damp hair can make assessment and controlled parting more difficult.
Bring the right reference
Save front, side and back views. Note what you like about size, length, parting and finish rather than relying on one image alone.