I like to sell my retired items so I can buy new things
Remember that you will be paying ebay (9%) and paypal (2.9% plus 30 cents) fees on the final value PLUS your shipping charge. Ugg. I don't undercharge on shipping or I would lose a lot of money. Anything over 13 oz that I send to the west coast will cost me 5-6 $ and over 1# can be 8-9$ and up plus the fees. So I try to estimate a mid range cost. After you have sold a few things, you will get a feel for the shipping costs. Or you can go to www.usps.com
and enter in some practice zip codes and weights. You get a slight discount on those prices by shipping right through eBay. Plus free delivery confirmation. I think eBay has an option to charge actual shipping, but people like to see the shipping posted. First class is very reasonable (13 oz or less), but factor in your shipping envelope cost. Priority boxes and envelopes are free - all sorts of sizes can be ordered online that are not available at your local PO.
I don't use a reserve. I just post the starting price at the minimum I want for it. Sometimes I will add a BUy it Now for those instant gratification people if I know the value and it's not a hot item that will get bid up.
Listing charges are in addition to the other fees. Ebay gives you 50 free listings a month. Take advantage of that, because you may have to list things several times before they sell. THey sometimes will announce a free listing day so be sure to be on their announcement email list.