Smell it - Does it smell pleasant? If so, what does it smell of? (tip - if it smells of dead dogs or london subways that's not good)
Taste it - What fruit can you taste? How acidic is it (how much does it make you salivate), how long does the flavour last, how many different flavours are there?
These are the basics to get you started. Plainly there can be a lot more to it than this and technical tasting will be dealt with elsewhere on the forum.
