Try to find a variety of shapes, sizes, and colors for the tomatoes. It makes the salad visually interesting.
Perline mozzarella is 'pearl-sized' and ciliegine is 'cherry sized.' In US supermarkets the smallest size of mozzarella is often called pearls.
You can either purchase the pesto or use your favorite recipe.
If you wish, drizzle some flavorful, extra virgin olive oil over the top.
I used a mixture of Speckled Roman, Green Zebra, German Johnson, Orange Jazz, and Golden Jubilee. Experiment with whatever varieties are available to you!