So...
first advice...
Just write. I assume you are just starting out. This will be a rough draft. Don't worry so much about these details just yet..but make note of things you want to look out for when doing your own edit after you've had a break upon completion of the book...(such as cliched relationship issues or interactions etc.)
Second...
Characterization is important... you can reveal alot about a character through characterization without action...meaning how one character is seen through the eyes of another character or even a random less important person in the story. What you reveal about characters and how depends on your point of view. Is it first person...etc...?
You could do yourself some good to read up on the essential literary elements of a story a story to get your mind moving in the right direction.