
How about looking at some optical illusions to remind that what you see isn't always what is actually there !
I've always said if you want to really 'see' things then go for a walk with a child or take a camera.
A walk with a child saying "look at that, look at this!" is quite illuminating - most of the time they will direct your attention to things you've never seen or noticed.
If you haven't got a small child (and can't borrow one!) then look through the lens of a camera and keep moving until you see something beautiful, unusual, funny, striking etc. It will almost undoubtedly be something that looked ordinary a few seconds ago or completely unnoticed.