Do you remember the rules for comparative and superlative adjectives? If you don't, see this video.

http://www.youtube.com/watch?v=cur13jaYnsA&feature=related

And here you'll find some exercises to practise:

http://www.ego4u.com/en/cram-up/grammar/adjectives-
http://anthonyhalderman.com/english/compsup.htm
adverbs/adjectives/exerciseshttp://www.saberingles.com.ar/curso/lesson12/05.html
http://web2.uvcs.uvic.ca/elc/studyzone/330/grammar/regcom2.htm