A logo is not your brand, nor is it your identity. Logo design, identity design and branding all have different roles, that together, form a perceived image for a business or product.
The company will likely not know exactly what they want, but know what they want once they see it. After you finish sketching some drafts, present them with about five of your best pieces, and ensure that nothing is similar floating around the market. Don’t add too much detail that will take up time; instead, keep things simple for the client to narrow it down, and then add to it from there.