Re: General suggestions for the future update, global trade...
I'm focusing on epic projects at the moment (worth it in the long run), so i'm currently not upgrading any buildings, and not doing any shipping/airport deliveries either. The items I make are all being sold in GTHQ. Because of this fact, i'm able to concentrate on producing the items that yield the most bang for buck. i.e., nails, Lighting System, Home Textiles, Caps, Donuts etc. I do have different items being built at day/night due to the limited commercial building slots.
When i'm off hunting for items in GTHQ, I pop a lot of bubbles in other peoples cities, these items also get sold for decent coins too.
Once i've saved up 100k coins, I can stock up on items I need to complete a gold epic project.
There's never enough of anything in this game, you need to concentrate on 1 thing at a time.