Deciding what to sell may not be as easy as you think. This is because we are reasoning with ourselves on why we should keep the item. Let's admit, we've all heard those voices inside our heads!
So, a tip to help is, decide on a reasonable time frame like 6 mos, 1 year, or even 2 years. Then, as you go through your scrap-stash, keep only those items you purchased within that time frame. Items purchased beyond the time frame should be added to your designated bin, box, or drawer (and keep it their!). If you haven't used it by now, chances are you not going to use it... and you most likely already bought something more current to use in it's place.
Also consider smaller quantities of one product. For example, if you bought a jar of flowers and there are 175 pieces in the jar.... ask your self are you really going to use all of them? If not, keep only what you think you will use and sell the rest. The same goes with brads, buttons, and ribbon. If you bought a spool of ribbon with 3 or 10 yards on it... keep for example 1 yard instead.
Be sure to go through your stash of 'used' product too. If you are holding onto stickers, thickers, paper, and other product with hopes that you might use them again one day, you should consider selling these items. Again, decide on a time frame. If you haven't used the remaining items in the last 6 mos or 1 year, then add them to your designated bin.
More tips to come on packaging, labeling, and pricing.