Hey Barb!
My DH (being a former chef) makes the best fruit salad in the entire universe.
Of course his will feed an army, but he always makes sure to add a citrus, (pineapple or oranges). The acid in these fruits will keep the others from turning brown (even the apples).
Some tips, use what you have in the house. Watermelon sometimes gets mushy after a while, strawberries will get mushy really fast if they are ripe (after more than 1 day).
Best ingredients (in my opinion) - cantaloupe, honeydew, watermelon, pineapple, peaches, plums, blueberries, blackberries, raspberries, strawberries (usually sprinkle berries on top) and whatever is freshest at your grocer. I don't prefer the apples in mine because they seem too crunchy with the other stuff (JMO).
Have a great day!