Marc Okrand wanted the language to be as complicated as possible. He did this to make it sound very alien. The word order in a sentence is always object-verb-subject. This is the opposite of English's word order, which is subject-verb-object. The English sentence "I see the cat" is said as "the cat see I" in Klingon.
This language uses affixation to denote the subject and negation:
Klingon
English
qet
run
maqet
we run
maqetbe’
we do not run
Writing
When writing in Klingon, some letters are always in uppercase and some are lowercase. This never changes because the letters are spoken differently when they are written differently.