For less desirable games, sell them as a lot but put a more desirable game within the lot. People are more likely to buy crappy games if it means they get a good one they are looking for.
If you decide to list them all as singles, you'll most likely get picked clean of decent titles and be left with a lot of games that you can't sell. This mainly applies to last gen stuff. IE: SNES carts, If you listed Super Mario RPG, Super Contra, Barney's Treehouse Adventure and Barbies: Lets go Horse Riding. You can pretty much garuntee which are going to sell and which are not. But meh, Ebay is a wierd thing sometimes.
Also to save a buttload on fees, if you have some patience i would recomend CTCW.