1. Having an item wanted by people on Listia properly priced
You want to acquire items wanted by newcomers to Listia. Every Listia newcomer has at least 500 credits and more if they connect their account to social sites and such. You want these people to bid on your auction.
So 500 - 1000 credits is the number that your item should be worth. Listia has no shortage of new members and will make you never run out of buyers. This means to stock up on things worth $0.50 - $1. This usually is codes that are for like props on Xbox, or a 48 hour Xbox Live code would work.
To attract your buyers I recommend putting 0 as your start bid, putting a high number will discourage bidders from ever clicking on you auction in the first place, even people that can afford more. When an auction is ending, bidders will end up actually putting more than what they intended when they first clicked the
auction. This is especially true for established bidders (think: high credits) and will get your item sold for much higher. Also, less whiny comments to deal with.