hardwood floor upkeep between tenants

[Angel S.]

I bought my first rental property in the last year, and I have some questions about maintaining the hardwood floors between tenants. When the existing tenant moved out there were some scratches in the hardwood floors, some light, some medium, and a possible gouge. I've read scratches can be buffed out and have poly applied to them. If I do this, would I need to buff out the entire apartment, or just around the scratches? For one gouge, would I just use wood filler and poly over it (same question on poly in that one area or buffing everything beforehand). What's the best way to apply poly? Is there anything I should do if floors still look pretty good between tenants?