From minimal to maximal with regards to adjectives.
1. One syllable: add –er, add –est.
Small – smaller – smallest
2. Two syllables (ending in –y, - le, -ow, -er): add –er, add –est.
Happy – Happier – Happiest
3. Two syllables (the rest): add ‘more’, add ‘most’.
Peaceful – more peaceful – most peaceful
4. Three syllables: add ‘more’, add ‘most’.
Extraordinary – More extraordinary – Most extraordinary
5. Irregular: depends on the adjective.
Bad – Worse – Worst