When I first started to sell online, there were three things that I found out very quickly.  Here is what I learned:

#1 The price of the item itself needs to be considered.  When I list an item to sell online, what I try to do is to make double on what I paid for the item.  This way I can have a little wiggle room if something happens like paying a little more than expected on something like shipping.

#2 You will be charged listing fees on items you put on selling sites.  On a site like Etsy, they charge a small fee to renew a listing after the item is on the website after a certain amount of time (there is also a fee when you are listing the item for the first time).  You need to watch it like a hawk—this can add up pretty fast and eat into your profits.  After one or two renewals, you need to think about adjusting the price or doing something like taking better pictures.

#3 Packing costs also need to be considered.  The packing costs will include tape, packing peanuts, and potentially the box itself (if you don’t get free boxes from places like the Post Office).  If you do not watch this area very closely, you can completely wipe out any profits if you are not careful.

What have you learned when you started to sell things online?