To properly pronounce Norwegian you will have to get used to certain "rules". One set of rule that causes some problem in the beginning, but soon is learned is the tendency of a vowel in front of a single consonant to become long, whereas it becomes short in front of a double consonant.
Samples of words with short vowel are: katt (cat), snakke (speak), spille (play), inne (inside)
Samples of words with long vowel are: mat (food), pen (pretty), hage (garden), hus (house)
To practise pronunciation the best is to use a Norwegian Teacher.