Norwegian adjectives are not very dissimilar to English adjectives.
The conjugation for most of them are: Mer (more) and Mest (most).
For plural the adjectives generally ends in -e. For the words in the example below the plural version becomes: "praktiske" and "normale"
Examples of conjugation.
Praktisk (Practical) - mer praktisk - mest praktisk
Normal (normal) - mer normal - mest normal
There are huge number of exceptions. However, the exceptions are generally based on the ending of the word and therefore something one will get used to after practice with the Norwegian language.
For example with -ig ending the word follow a particular pattern.
Alvorlig (serious) - alvorligere (more serious) - alvorligst (most serious)