Feedback is very important on ebay, but there are ebooks out there that advice people to break ebay rules.
Dont just buy or sell dozens of one penny ebooks - this isnt allowed as it is false manipulation of feedback.
It is very easy to find a few items around your house that arent wanted so list these, and find a few items you need on ebay as well.
Its okay to buy a few ebooks, but make sure they are about something that interests you.
It is worth buying several ebooks about selling on ebay as there are some usefull tips and easily worth a penny.