Add vegetables that you like. Wash and chop a few veggies to toss into the salad. Add interesting flavors, such as tomatoes, celery, and herbs (Fresh is best).
According to one source[1], avocados, almonds, broccoli, and apples are among the "Top 10" healthiest foods, so consider adding these to your salad.
Don't add "too many different ingredients" to your salad.
Healthy options for your salad include:
bell peppers
goat cheese
carrots
cucumbers
pomegranate seeds
mozzarella cheese
figs