For starters, make sure it’s not too busy. If it contains a design, a business name and a tag line, that’s probably too many elements. Start with a simple but interesting image and font and get feedback from a lot of people before deciding whether to go with it.
Study other food trucks around the country as well as trucks in your area to see what they do and then try to differentiate yourself without going too far. And by all means, if you aren’t a graphic designer consider hiring one; you don’t want your logo to look like it was designed by an amateur.
You may not wind up with the next Golden Arches or Olympic rings, but with any luck you’ll get a logo for your food truck business that symbolizes what you do and makes a lasting impression in the process.