What are the best ways to fit in transportation and reduce the cost?

Cost reduction is possible with a proper route plan of daily deliveries. which will result in less returns and so more customer coverage.

Cost per case or per delivery will be less if more deliveries or cases are delivered to customer.

So concentrate of preparing a better route plan, if we are talking of domestic deliveries.

do an analysis on how many volumes you are producing and accordingly calculate how many trucks you need on a daily basis to move your cargo. Having a dedicated fleet of trucks paying on monthly basis instead of daily should be cheaper depending on how reliable your production is.

Start a bid in the market for transporters to provide their best rates and provide them with your scope of work.