I'm currently writing a story but as a second speaker of the English language, I'm not sure about a lot of things like how to describe the evil Grin villains give, what is the expression used when a guy is flirting, what is a moan, how to tell that the character is annoyed, how to say when we are extremely angry, what is a smirk and a whole lot more.
Smirk: Smile in an irritatingly smug, conceited, or silly way. Moan: A long, low sound made by a person expressing physical or mental suffering or sexual pleasure. Words that mean extremely angry: livid, furious, enraged Evil Grin: "Sadistic" means "enjoying others pain" so you could call it a "sadistic grin". A maniacal grin works too - a manic is someone who is very violent or angry, also normally crazy. Or a demonic grin (demonic meaning evil). anything else you need help with?