How to sell to retailers? As a former Retail Buyer from Target, here's my suggestion. You need to first ready your sales communication and materials to explain how 1) You will drive sales at their stores (best told through sales traction and history in comparable or slightly smaller retailers than the one you are targeting 2) Demonstrate how you will support sales with a marketing plan. Marketing mitigates sales risk and that's a retailer's #1 concern and 3) Prove you will deliver flawless vendor execution. There are many hiccups that happen along the supply chain and it takes an experienced company to flawlessly deliver inventory to the right stores/DC's in the right quantity on the right day. The best way to prove this is by showing that you are currently working with retailers of the same magnitude. So in short, you have to scale up slowly - from small retailers to larger retailers - in order to manage risk, build sales traction, build brand awareness, and manage cash flow.
How to contact them and sell to them? Use Linked In to find retail buyers. I have a short video on how to do this: https://www.youtube.com/watch?v=ZwbfUMRHiq0 Trade shows are also effective; you can get the mailing address of retail buyers in attendance plus meet them face to face if they come to your booth. Also, network within your industry. You'll find your peers are wiling to trade buyer lists with you. But in short, don't bother reaching out to a retail buyer until you have talking points that address those 3 things I mentioned above all.
I'm happy to do a clarity call if you have follow up questions.