• Avoid food with a high percentage of calories from fat ( > 20% ) (and yes, all meat falls under this category)
  
• Avoid food that is filled with chemicals (e.g. anything that's neon blue or has long words that you don't understand on the label) (and yes, all soft drinks fall under this category)
  
• Be sure to vary your diet -- don't eat the same things all the time and cover all of the food groups (wouldn't you get bored if you didn't do this?)

• High percentages of fat cause heart disease, cancer, strokes, and much more.
• Chemicals are totally unnatural, totally unnecessary, and usually increase your chances of getting cancer.
• Animals get their nutrients from the plants they eat -- so why not skip the animals and eat the plants ourselves?
• It's really easy to follow the tips!

I might add: becoming vegetarian, while very easy, is not as simple as just discontinuing meat consumption. To be healthy, your diet has to be modified to include enough calories and enough nutrients. Don't be surprised if you eat more than you used to!