Although I've sold plenty of stuff on eBay (including iPhones), I always treat it as a last resort.
My preferred way to find a buyer for my old tech is in person - usually at work. An email to my colleagues, followed by a posting on our intranet if there are no takers, normally finds me a buyer. For my colleagues I charge less for a quick sale (i.e. I'll let them know that if there's no interest in the first week then it'll go on the intranet at a higher price).
Failing that, an email or Facebook message to friends and wider family is my next step - quite often someone is on the lookout for a cheap camera or computer for a parent, and as long as it works they're not fussed if it's the very latest.
Finally, if you belong to any groups/clubs etc then an email or posting on their website is worth a try.
Only after trying all that do I resort to eBay. With large kit, like a computer, shipping can be high and offputting, so I'd start by putting a Buy It Now price with free, or cheap, shipping. Research other (successful) completed listings for the same item and price yours accordingly. Ignore the very highest and very lowest sales - it's better to sell for a slightly lower price than not sell at all.
Be honest about the state of the item, explicity state what is and isn't included, overstate any scratches or defects (better to do that than be accused of hiding something) and put up LOTS of photos. The more detail you give, the more comfortable people will be buying or bidding. Do NOT use stock photos off the Apple website - take your own photos, and use a decent camera. By doing this, I've sold items for a higher price than others, purely because - I assume - people felt more comfortable with my item than with one that just had a stock photo and no description.
If it doesn't sell as a BIN then go for auction - my preferred method here is a low start with a reserve. Check the fees eBay charges - last time I sold something you paid more for a higher start price.
Finally, read up on eBay's seller protection and make sure you understand what you need to do to stand the best chance of eBay covering you in the event of a problem - but accept that you may well end up with no item and no money. It's never happened to me, but a colleague lost an iPad and the Paypal payment because the "buyer" claimed his account had been hacked.
As for your feedback, it depends on the buyer - some will just see "100%" and be happy; others will wonder why you've never sold anything and be a bit wary. However, since your first sale is an old, low-value item (it's not an iPhone 4 or an iPad 2 for example) it does look reasonably genuine. Every seller has to start sometime! And again - be honest and open. Ask for, and answer, questions. And don't hide ANYTHING.