It's vital to stipulate your requirements in a contract! Even if it's things like requiring vendors to use certified compostable, recyclable or reusable packaging, it's important to state up front.
Programs see lots of great success when they work with amazing partners. Find partners that support similar things that you do and it is sure to be a match made in heaven.
Consider incorporating both text, visuals, and color coordination to get your message across. This will help guests understand and recognize what goes where.
Make educational opportunities fun. A great way to do this is through gamification. Turning education opportunities into competitive activities is one of the best ways to create change.