If it's for an OC/book character/etc that doesn't have a visual design yet, you're welcome to send various images for face inspiration, hair, fashion, scars, etc. There might be an additional design fee in that case, but that just means I'll go back and forth with you on one image until it looks right, then we'll move on to the rest. If they have a design just not a reference sheet, then I find 1-3 images is a pretty good number. The form to fill out on that linked site will walk you through that.