I would recommend that you take the time to set up ALL the profiles and settings, including the shipping/payment details, and checkout options, before you start on a listing. One thing I have found to be most beneficial is to set up a separate Master Profile which has all the individual profiles I want to use for a particular type of listing.
I have set up individual Item profiles for New Items, Books, Vintage Items, etc. Each of these has different "pre-set" information and formatting, plus a different template, so all I generally have to do is fill in the pertinent information about the item I am listing, save it, and move on to the next!
Set up one or more Marketing Profiles, Shipping Profiles, and Checkout Profiles. If you use Gallery pictures on some types of listings but not others, then set up at least two profiles for that.
I have a Master Profile set for Store Listing of New Item, Store Listing for Books, Store Listing for Vintage Items, Auction Listing for Books, Auction Listing for Vintage Items, etc. Each of these Master Profiles has a particular Item Detail profile, Marketing Profile, and Shipping Profile, but they all have the same Checkout Profile.
To make life easier, do all the profiles FIRST. Then do Master Profiles. Do some playing around, creating some "test" type listings that you save [do not use the Save(Post), otherwise it will post the test listing to eBay and you are stuck paying the fees.] Your profiles might need to be modified after you see how the whole thing looks. That's natural.
When you've got all the profiles just right, then use them to create your listings.
I know that you might be in a hurry to use the great Auctiva program to get those listings up and running, but a little time spent in preparation will greatly pay off in a reduction of frustration and mistakes if you jump in immediately trying to list before getting things 'just right'!
One last thing, if you want to offer your customers combined invoicing, then you will want to NOT have Auctiva checkout selected. Be sure to change that setting, because the default is that Auctiva Checkout is set ON. At this time Auctiva doesn't have combined invoicing capability, though it seems to be planned for future upgrades.
Hope this has helped you.