Proper way to ask a teacher to become their student

I'm seeking a meditation/dharma teacher to help strengthen my practice, once I find one and establish some relationship what is the proper way to request becoming their student. I'm interested in The etiquette for lay or monastic. Also where I am there is not a strong community of practice what suggestions if any does anyone have about online teachers/instruction? (Hazards/cautions) if the relationship has to be long distance what steps can I take to make it more beneficial?