Both tenants voluntarily help to maintain the property -- grass cutting, snow removal, keeping sidewalks clean, repainting their apts, etc.Does anyone have a strategy to suggest?

I run a large graco sprayer when I first acquire a property to do a total repaint and have a small wagner sprayer for touchup.

Depends on your location and how pushy your Attorney is.Now you just have to deal with removing trash, making repairs...some big, some small; usually count on complete repaint, and often, new carpet.

So far we just wanted to repaint the walls, change the living room floor from carpet to vinyl, and repaint the kitchen cabinets.However, we are not sure if that's enough to attract good tenants (for a 3 bed, 2 bath detached home with a pool in Kissimmee area), or should we spend more time and update the countertop (not sure how it's important for STR), kitchen cabinets, bathroom vanities, etc..Since we are out-of-state investors, the less amount of effort and money we can spend to get similar results in term of rentals, the better for us.

I did replace the flooring throughout the home with a good quality vinyl plank in 2018, repainted the cabinets and added hardware, and updated some fixtures before moving out.

I repainted a red dining room once and my first tenant said she would have liked it red.

We replumbed the house to accept tradition floor mount toilets, tiled all the bathrooms, replaced bathtubs, changed kitchen layout and retiled kitchen floor and counters, repainted the entire interior of the house (bought a professional airless paint sprayer) and replaced all carpet.

I spent $6k on a roof last summer, $800 on a water heater two months ago, $500 on a range 18 months ago, $2500 on an AC a couple years ago, $3000 on a furnace several years ago, several repaints, drywall and bathroom repairs, new carpet, etc.  

Most of the interior has been repainted.

@Russ O'LearyUnder no circumstances let her smoke inside unless you plan on doing a complete wall scrub and probable repaint when she leaves.