I probably did what most people don't do right away. I wrote my profile and policies first. I browsed through different shops' policies and got a grasp of what was commonly an issue and composed mine from there. A lot of fine tuning but not at one go. I just kept going back at it to keep myself refreshed when composing it.

Then the costs. Since I'm starting out with selling prints of my film photos, I had to gather rates of different labs and different printing options. I also had to know what print sizes are best. More research and asking people around.

Shipping can be a great deal too especially if you're doing this for the first time. I checked the etsy and ebay forums to find out how sellers ship their items at the best possible rate and at the most decent time frame.

Next is packaging. How do I package my stuff? Where do I add the cost of the packaging materials, on the shipping cost or the product cost? Do I need to put labels? How do I protect it from damage? --Well, what's best is that all the answers to these can be found in the etsy forum. You won't even have to start a thread or make a reply. Most of the time the answers are already there. Just make use of the search function.    

As to what photos were best to go up first, I referred to my Flickr stream and chose what was interesting to a lot of people.

I haven't made a sale yet since I just officially opened yesterday. I received hearts though, and that made me soar! 

~The forum has a vast coverage of topics. Very very helpful

~Use the search function! A lot of times, there are multiple questions asking the same thing.
~Do not limit yourself to the etsy forum. I found ebay really helpful. Also flickr.

~Ask. Even people you don't know. Flickr, blogs, craft forums.

~Purchase a weighing scale. It will help you with giving accurate shipping rates.

~Use all 14 tags