Something all people trying to sell their Cd's online should consider is digital distribution.
This is a tip that CD Baby also gives so I'll give the credit to them even though I thought of it long before they said it.If you type your name and or the name of a song into one of the p2p networks and you actually show up it is a big plus for you.
Yes it means that some folks are getting your music for free but the marketing value is way beyond that problem.
The problem we all have selling on the Internet is number one there is so much stuff out there.Quite a bit of it is very good.Someone said on here that is is hard to sell what people cannot here.That is very true.
It is important to do some cover songs for several reasons.
A very important one is that when people are looking for a particular song and your name comes up on that title then they listen to it and like it,they will want to know what else you have done.
Marketing is the greatest cost factor in selling anything and anytime you can get your name out there you need to do it.
Good luck,I hope you sell a million.