Compound adjectives with hyphens in them include:

adjective/adverb + present participle
a hard-working student, a good-looking girl

ages and numbers before a noun                                                                                                             
eighteen-year-old students, a two-door car

compound numbers from twenty-one to ninety-nine
fifty-one, seventy-nine

Compound adjectives can be formed in other ways, for example:

adjective/adverb + noun
a last-minute decision, a one-way ticket, full-time job

noun + adjective
a world-wide web (www)

adverb/noun + past participle before a noun
well-respected teachers, a battery-operated device

three-word compound adjectives before a noun
an out-of-date product, an out-of-work father

Compound adjectives without hyphens include:

adverb/noun + the past participle after a noun
the teachers were well respected, this device is battery operated

three-word compound adjectives after a noun
that product is out of date, his father is out of work

compound adjectives made with an adverb ending in –ly, both before and after a noun
a carefully written letter, the letter was carefully written

Compound nouns do not usually have a hyphen, for example:
senior university, secondary school, swimming pool, ice cream

But a few compound nouns are hyphenated, for example:
t-shirt, mother-in-law