If you are "clueless to the value of coins" and "selling a lot of coins", you should probably get these coins appraised by a professional. You could also do some research on your own to get a better idea of the values. However, selling items you have no idea about the value is probably a bad idea. I wouldn't sell my car without assessing a value to it first. You might get lucky and somebody will pay you excessively more than the worth, but it's more likely you will be taken advantage of. PS Disclaimer: Don't Clean Your Coins.
Aw, don't go offerin' that fella some old bridge in Brooklyn. We have a much nicer and newer one here in the Golden Isles.