I have noticed over the years that the foods and drinks I have even a couple of hours before I play have a profound effect on my lip and over all trumpet playing. For example, Salty food or drinks decrease the flexibility of my lip. Likewise, Fatty foods decrease the flexibility, but also the low and upper range as well. Drinks or foods with alot of artificial ingredients definitely decrease the over all performance and endurance of my lip. Drinking plenty of water before and during playing helps greatly overall. When playing in large crowds by myself (yes, I still get a little nervous even after all these years) I found drinking fruit juices like cranberry, apple or even better orange juice (with low acid seems the best) helps calm the nerves and gives me the performance I'm looking for.
A side note: getting plenty of rest and calming the mind and body before playing also helps greatly..classical music is the ticket for me.
What other foods, drinks or routines do you perform before performing before crowds to maximize your trumpet playing.