1. I have always struggled with knowing when to put a hyphen in a word or to combined two words.

2.

Generally, hyphenate between two or more adjectives when they come before a noun and act as a single idea.
Examples:	friendly-looking man  (compound adjective in front of a noun)
	friendly little girl  (not a compound adjective)
	brightly lit room  (Brightly is an adverb describing lit, not an adjective.)

3. For the grammar rule link click HERE.