I try and get as many keywords in one keyword as possible.

"Dog's tasty chews" has "Dog's tasty chews"* and "tasty chews"

"Tasty chews for dogs" has "Tasty chews for dogs", "tasty chews" and "chews for dogs".

The first one only has 1 variant that is "dog specific"* to the product (chews), the second has 2.  I don't put an adjective after a noun, the word "for" keeps cropping up in my keyword research as being useful.

I go for singular (people aren't looking to buy your whole stock just one item from it).

"Piano" 450,000 Global exact match, low competition.

"Pianos" - 27,100 GEM high competition

Awesome!