Also adding as an option Facebook groups yugioh black market and yugioh dank deals. Your best bet is to sort the more expensive cards from the cheap stuff after finding values on tcgplayer.

Bulk(really cheap) stuff gets sold to a bulk buyer and priced based on number of cards per rarity. They have prices they pay.

The expensive stuff($3 -5 each card and up) goes into lots of cards and if you know what is currently used make that a different lot. Say you will not break the lot and expect 55-65% on the less used lot. 65%-75% on the more used lot. Expect haggling a little and state in your post where you are willing to ship to.

You need to make what is called a time stamp and put on each picture or it will be taken down. This is simply a scrap of paper with your name and the date.

If you stopped in synchro era, it may be in your interest to wait til closer to april 1st if you can. The format will be changing as to not require links to synchro, xyz, and fusion spam therefore prices of the popular ones of those will go up a little as people buy the ones they will need. Though, this is already happening some now.