Smoothies - help!

Seakay

Another thing that you should probably emphasise is that smoothies are more of a liquid snack than just a drink. Janet Street Porter made the mistake of assuming they were drinks on one of Gordon Ramseys show, and then compared them unfavourably in terms of calorific value with fizzy drinks laden with processed sugar.
The point about a smoothie is that it contains one or two of your suggested five a day fruit and veg, it shouldn't need to contain processed sugar so the fruit sugars etc that it contains will release more slowly and give energy for longer. They are better than plain juice because they contain fibre as well.
As others have said, bananas, fresh or frozen are great for thickening. Any soft fruit, fresh, frozen or defrosted can be used. Basically, if it can be liquidised and you like it then bung it in! The reduced corner at the supermarket or the freezer is a good a place to get ingredients as the fruit counter.
Adding (plain live) yogurt will add creaminess and a little protein
http://www.annecollins.com/protein_diet/protein-yogurt.htm
If you want to add orange, apple or pear then it's best to add them to the mix as juice.
Innocent Smoothies have published a book of recipes - order it from your local library or have a look at the pdf online for combination ideas. When they use orange, apple, grape or pear juice in their recipes then use some from a carton rather than juiceing the fresh fruit (which can work out very expensive)
I like to make a thick milkshake type smoothie with soya milk (the sweetened type) for added nutrition
http://www.soya.be/nutritional-values-of-soy-milk.php
(you won't taste the beaniness over the fruit and it makes the finished article very creamy tasting but very low fat). Tesco's organic is Soil Association approved so you don't have to worry about GM foods or the rainforest being decimated.

One big smoothie for me is:

1/2 pint sweetened soya milk
1 small banana
1 peeled kiwi or a handful of frozen fruits of the forest or 1/2 a peeled mango or some reduced blueberries or some frozen raspberrys etc etc
All wizzzed together.
If it's not sweet enough then sweeten with honey rather than sugar, but as long as the banana is ripe then it should be fine as it is.