Gameplay question

I split my production between the airplane, train, helicopter, and zoo orders. I am level 41 with three trains and fourth ranked in airplane orders. I’ve noticed my helicopter orders are getting harder to fill with current focused and attention. I guess my goal is to level up, upgrade my factories, and make coins to spend on decorations and buildings. (Although I have mixed feelings about fully developing the land lol thoughts for another post). What strategy is best to achieve my goals? Should I focus on loading trains and helicopter orders till I am more developed to handle four exports. Also I visited a farm and it looked like their zoo and town had combined. Is this possible to achieve? I would love to have my town and zoo together and if this is possibility my goals might change. Thanks for you help! Also interested in any thoughts on strategies that are unique to you and your gameplay!