This is a tough one to cover. I think it takes a lot of reading to get used to when to use them. For example, the cat doesn't have blue green eyes, she has blue-green eyes.
There are literally gobs of times when you should use a dash between words. Some phrases are built-in (like built-in!) for dashes, such as thirty-five. All numbers in the 20s, 30s, 40s, etc. have a dash. Forty-four. Seventy-seven. When you add hundreds or thousands, you do not use dashes except for the smaller numbers. For example, one hundred thirty-five cats are too many to have in an apartment. Two thousand ninety-six cats will breed and make eight thousand fifty-six cats.
The best way to learn how to use dashes between words is to read and pay attention to when you see them. Your brain will absorb the examples and your writing dashes between words will improve.
