My suggestion:
+ One time purchase (per account), I would VERY gladly pay $20-25 upfront for this game, if I know my gameplay and playtime are fully unlimited afterwards.
+ Include all the cosmetic things mentioned in this thread
+ Add consumable, non-refundable items to the store (Something like springs in salem or the current flint & steel, as in, items that you don't really need, but that you would much prefer to have).
+ Limited time, non-refundable and transferable cosmetic purchases (because tbh a permanently kept cosmetic item is worth much less than a cool item you can only buy for a short period of time and then have no way of obtaining it after it's gone). Stuff like capes, special limited time "skins" for other items, and basically any other things similar to the cosmetic items already suggested (this time, with a limited time twist to them though). Maybe even limited quantity too.
In a nutshell:
* Guarantee that the player will atleast have to purchase the game at some point if they enjoy it. That's guaranteed profit.
* Add items that are nice to have, but not really required. Items that make some mechanics less annoying, but give you no real advantage otherwise.
* Play a lot with the store, convince players to buy items. I'm sure that as long as this game isn't made into a blatant pay to win, people won't mind you guys selling flint & steel, or village decorations or anything of the sort.