Interior Design / Furniture layout

Need quick help with furniture scale/placement/layout for a small-ish combined living room/dining room in an NYC apartment. Want to maximize seating/lounging area, possibly a corner sectional but can't determine appropriate dimensions to shop for. Also need help with sizing of dining table, coffee table, etc. Welcome suggestions for specific pieces, but could also hunt for them myself once I know what I am looking for. I don't trust my sense of scale and don't want to overwhelm the space!!