Once you have your store set up you need to get some pieces to inventory. Everyone has a different way to sort. I have changed the way I sort many times. When you get a large lot of parts like this to sort it can be daunting.
I sort according to Bricklink’s categories since it is how I have to list the pieces. I usually start with a few of the big categories first. Bricks, Plates, Slopes, Tiles and Wedges. I have this checklist on the totes that I store pieces in. When I sort out the categories I check it off with a dry erase marker so I know what has been done in that tote.
I will go through a box of parts and pull out all the pieces that fit in those categories. No matter what the size or color. This five main categories I might just put all together in a tote depending how much I have to sort and separate them further later.
I have two Ikea kitchen cabinets with six drawers each. The boxes are from Ikea as well. When it is time sort down to the part level I sort into this boxes. You can use anything but I like that I can keep the parts in the drawer and shut it when I am done. The above pictures is all Plate Modified. At least with these pieces I try to keep each box a different piece but will put some together to save space. For the Animal categories I put them all together.
When those bins are too full I will either bag them up to inventory later or I will take a bin and sort it out by color. At this time I will check the condition. If it is too scratched, has bite marks or discolored the piece is discarded.
I use trays from the Master Builder Academy sets. I got a lot from a seller on Bricklink some years ago. I use zip bags as well. Other sellers use cups or make a custom sorting tray. Find whatever works for you and works for your sorting area. Now it is time to enter the pieces into my store.
The only thing that I never do is sort by color. I did it once. I had a very large amount of pieces to sort and I had help. Instead of trying to explain all the categories to everyone it was easy to say pick a color and bag them up. It was a lot of extra listing because I had to look up the same piece every time I did a new color. It worked for that situation but I will never do it again. Also never store the parts in your store by color for the same reason.