We actually just started this, and we love it! It has made everything so much easier!
We have the inventory written down right now, but we are going to be putting them all in Excel. We have started at 001 and have just kept going up when we purchase a new item to sell. We have columns next to each item that have the weight, description, and pricing references so we can price it correctly when we post. When we do post, we put the number at the very bottom of the description, so it is out of the customer's way when they are reading. Hope this helps!