Press your lips together, add vocal cord vibration, then release.

Americans pronounce bookstores as BUUK-storz (/ˈbʊkˌstɔrz/). Stress falls on the first syllable — keep everything else short and quick. You'll hear it in sentences like "I enjoy browsing through the shelves at independent bookstores".
Record yourself saying "bookstores" and play it back. The mic stays on your device — nothing's uploaded.
2 syllables, 7 sounds. Tap a syllable to jump to its row, then explore each sound's mouth shape and how it's made.
Press your lips together, add vocal cord vibration, then release.

Bring the corners of your lips in slightly so they push forward, but keep them relaxed. Lift the back of your tongue toward the roof of the mouth.

Raise the back of your tongue to touch the soft palate (velum). Stop the air, then release.

Place your tongue tip near the roof of your mouth behind your top teeth. Push air through the narrow gap. No voicing.

Touch the tip or front edge of your tongue to the roof of your mouth just behind your teeth. Keep your jaw relaxed. Stop the air, then release with a puff.

Start with the 'aw' jaw drop and rounded lips. Pull the tongue back and up while keeping the lips rounded for the R.
Same position as S, but add vocal cord vibration. Feel the buzz.

The textbook way isn't wrong — it's just not how anyone actually says it.
Stress falls on the first syllable, not the others. Stretch BUUK — keep everything else short and quick.
Americans use a relaxed retroflex R — the tongue curls back rather than rolling. The R is one continuous sound with the vowel before it, not two separate sounds.