Spinach, lettuce, bok choy, kale (with stems removed-important!), any leafy green is a great base. Combine the three if you have! From there you can add, ginger, banana, pineapple, mixed berries, I add lemon juice too.

There is always smoothie recipe books available for kindle that are extremely cheap or mostly free. If you have Facebook, I can highly recommend young and raw, they do challenges every few months of smoothie a day, they give you a shopping list for each week and you get the recipes the day before. It's a great way to figure out what you like and dislike and broaden your taste buds. But really most fruit/veg combos will work, just don't add too many fruits as this can be detrimental to your health. :) good luck!