What I do next is separate the books into age groups. To determine the age group I looked most of them up on Barnes and Nobles website under the product information. For some reason Amazon doesn't often have that information. After handling children's books for a while you'll be able to tell what age group it is just by the thickness, size of text and whether it has chapters or not. Most of the books I bought fell into the following age categories: 3-5, 7-10, and 9-12.
I usually list books in lots of 30 - 50 books and try to get 75 cent to a dollar for each book..sometimes a little more than a dollar. It depends on the age group and size of lot etc.
Large lots of series can be very lucrative but unless you get a complete series in one buy they require storing the books as you build up your lot. I don't focus on those.
The next step is photographing and describing the books. I usually photograph a stack of them for the gallery pic and then photograph them in groups of 3 or 4 so that each title is pictured. You can also scan each book so it is a nice thing to be able to do if you are working at night and can't take pictures due to lack of light. If it's a smaller lot I list each title in the description. If it is a larger lot I don't. I figure people can look at the pictures to see what titles are there. I then describe the condition of the lot as good to very good as I just don't pick up books that aren't at least 'good'. Below I've copied Ebay's definition of 'good'. I also note that some of the books may have a previous owners name written inside. Ex Library books are worth less and it should be noted if your lot contains any of those as well.
A book that has been read but is in good condition. Very minimal damage to the cover including scuff marks, but no holes or tears. The dust jacket for hard covers may not be included. Binding has minimal wear. The majority of pages are undamaged with minimal creasing or tearing, minimal pencil underlining of text, no highlighting of text, no writing in margins. No missing pages. See the seller’s listing for full details and description of any imperfections.
Keywords are also important when listing books. People sometimes look for lots that contain medal/award winners and books on the AR Accelerated Reader list. So if I've got those in the lot I put keywords in the title to reflect that like AR, Newberry etc. Here is a great website where you can check to see if a title is on the AR list. Award winning books usually indicate on the cover which award they have won with a seal, like the one below.
Other keywords that are useful are 'teacher', 'home school', and 'library'.
The start of a school year is the best time to sell them as teachers build up their libraries and home school parents purchase their books. I list them all year. You can also put together lots for holidays. I've sold several lots of Christmas books. Right now I have listed a lot of Valentine books and a Black History lot.
Bookselling is quite a bit of work and takes quite a bit of storage space but if you enjoy books like I do you may want to check it out. I currently have 173 book listings in my store. Most of them are listings for just single books that will sell for enough on their own so they don't go in a lot. Now that I do not have a good source for cheap books I'm looking to clear out my book inventory. I will still keep my eye out for vintage and specialty books but probably won't be selling in lots.
I hope this was helpful for anyone thinking of selling books. If you have questions or helpful tips post them in the comments.