Friendly Tips for Successful Book Selling Online: Wrote these up for a discussion forum and thought would post here as well.
* I only sell through Amazon. It was too much work juggling multiple outlets and Amazon has by far the highest sales speed/rate.
* I only sell if the lowest "used book" price is $10 or more. Pick your own floor but even at $5 you are barely going to make a cent.
* Check the Amazon sales rank on a book. (Once you are a registered seller you can see this when you click on the "Sell On Amazon" button.) A sales rank of 10,000 or less will sell very fast, a sales rank of 1,000,000 may not sell for years, if ever.
* I buy postage and print shipping labels through Amazon because after shipping many books using my own postage and meticulously calculating weight and various stamp denomination combinations and procuring said stamps, I decided my time was worth the few cents they take off the top.
* I highly recommend investing in a good food scale for weighing packages. (Postal scales tend to be lower quality and you have to replace the dials when the postage prices change.) The difference between a 12 oz book and a 15 oz book will cost you money.
* If you choose to do your own postage, print out the current media mail rates and keep them near your shipping supplies.
* I almost always ship in recycled envelopes or cut up brown paper bags. Buying envelopes cut into profit margins; buying shipping tape also cuts into profit margins.
* Keep all your sale books in one place. Do not tell yourself "Oh, I'll list it but I want to keep it on this shelf instead of in my for-sale pile."
* Keep your shipping supplies all in one place.
* There is an Amazon Seller app, but I find it tricky because it often suggests a high profit margin but later research will reveal it's a $0.01 book in another format or edition.
* If you start buying books specifically to sell, also create an Excel spreadsheet documenting true costs at all stages. There is virtually no margin in book selling so you have to see clearly what brings in what income and what costs you are really incurring.