Things I usually eat include:
-dry cereal
-bread
-crackers
-pretzels
-celery
-oatmeal/porridge
-apples
Basically it's supposed to be good to eat carbohydrates, protein, and fiber (bread, pasta, bagels, fruit, granola bars, yogurt, crackers...etc) before practice. I don't pay any attention to that and eat mainly bland foods that don't make my stomach upset.
Don't eat too much before practice, only enough so you no longer feel hungry. Good idea not to eat anything that is very processed and rich (i.e. cake, some cheeses, ice cream, fried foods, microwaved meals) because from experience I can say it makes you feel heavy and "bleh", for a lack of a better way to describe it.
For after gym, I eat whatever the rest of my family had. And something unhealthy to top it off, hehe.