The basic rules of forming comparatives:
> One syllable words take " - er". Look at these examples: clear - > clearer, sweet - > sweeter
> Multisyllable words take "more". Look at these examples: incredible - > more incredible (not "incredibler"), horrible - > more horrible (not "horribler")
> Two - syllable words ending in consonant + y take "ier": Look at these examples: happy - > happier, pretty - > prettier
Some words can take either - er or 'more': Both "more clear" and "clearer" are acceptable.