
Reflecting back on the Level 1 Guide, by design, you can't do everything in this game. The developer's hope is that you purchase solutions to be able to do everything.
At this point in the game, you are now given 4 different materials in contracts that you need to manage, with 2 more coming at level 14.
Materials are the foundation of growing your farm. They can be broken down into 3 categories:
You can generally do 2 categories well, but not 3, so I would suggest you pick a first, second, and third priority. For me, having studied the game and played its predecessor, I recomment upgrading as your first priority, followed by expansion. This is fluid and changes as your farm grows. Sometimes, you will focus on expansion or research. You will 'passively' collect your lowest priority items if you follow the strategy below.
A very simple and easy strategy for the market is the Rule of Three. (My personal application is in brackets - yours will be different)
Divide all your materials into 3 categories:
Then divide all your products into 3 categories:
Now the magic:

You will often have to dump a contract that you are fully able to complete. This is necessary! Trashing contracts that ask for Hard-to-get products for Low Focus materials (like Books) ensures you conserve your product stock to immediately fill future contracts that offer High Focus materials (like Glass). Embrace this short-term sacrifice for guaranteed long-term resource optimization.
And just to repeat myself, the barge 'looks' like it gives more materials, but that is because you are sending way more products at a time. Per product, the barge gives half of the materials.
One of the things I have noticed with this Studio is that products will be in higher demand after they are introduced (1-2 levels), or when a new stage of the product line is opened up. You may find that when sunflowers are needed to make seeds, suddenly their interest in the market goes up. I really wonder if it is just to cause panic expansion and spending. They do tend to level out after a few levels.