here are some other things to use:
1. Fruit as the 'base' - bananas, strawberries, pineapples, kiwis are good. Blueberries are OK, but the skin will be similar to pulp in orange juice so don't use them if you want it really smooth
2. A liquid to help things blend. Try milk, fruit juice (apple juice is nice because it wont overpower the other flavors) or just water .
3. A thickener. Something like yogurt, ice cream, frozen fruit, or ice cubes.
A good rule of thumb for measurements is 1 part fruit, 1 part liquid, and 2 parts thickener. So for a 1 cup smoothie, you would use 1/4 cup fruit, 1/4 cup liquid and 1/2 cup thickener.
If you use ice cubes, make sure you get a blender that can chop them, otherwise go with the yogurt to make a good consistency