To contact your host, first check your booking confirmation or the platform you used (e.g., Airbnb, Booking.com) for their preferred communication method. This often includes a messaging system within the app, a phone number, or an email address. For urgent matters, a phone call is usually best. For general inquiries or non-urgent issues, using the platform's messaging system is often convenient as it keeps a record of your communication. Always be polite and clear in your messages, providing any necessary details like your booking reference or the nature of your query.