You could spend your points on rubbish if you want, although on the rare times I've done that I always end up feeling ill...
If you use the e-source (which I do) you can point everything or can use the leaflet they give you at class which has all the basics. I eat lots of point free stuff to make sure I get my five a day - munching on carrot sticks and raw swede when I get into work, having a good portion of veg with my evening meal etc. I try not to eat too many of the ready meals (WW or other low cal ones) as they're high in salt and low in nutrients, if I do I usually have veg with them to make them look a good size. I do leave some points spare so if I fancy something sweet I can eat it - I like the chocolate bars in class at 1.5 points or the chocolate highlights (little bags of chocolate halos) for 1.5 points.
WW has taught me portion control and good meal planning as well as trying to make my points stretch as far as possible... My big advice is to write everything down...