The Trading Post is more than just a place to buy and sell; it's a dynamic economic tool. Pay attention to merchant types: some specialize in raw materials, others in food, and some in seeds/livestock. Anticipate their arrival and prepare your trade goods in advance. Always aim to produce a surplus of high-value goods (e.g., Ale, Wool Coats, Steel Tools) to trade for essential items you can't produce or for rare seeds/livestock.
Don't be afraid to buy and sell strategically. If a merchant offers a good price for firewood, sell your surplus and buy something you desperately need, even if it's at a slightly higher price. The market fluctuates, so learning to read the trade opportunities is a 'secret' to long-term prosperity. Building multiple Trading Posts can increase your trade volume and access to different merchants.