Round your lips into a tight circle. Lift the back of your tongue toward the soft palate and add voice.

Americans pronounce wisdom as WIHZ-duhm (/ˈwɪzdəm/). Stress falls on the first syllable — keep everything else short and quick. You'll hear it in sentences like "Observe the wisdom of the wizard closely".
Record yourself saying "wisdom" and play it back. The mic stays on your device — nothing's uploaded.
2 syllables, 6 sounds. Tap a syllable to jump to its row, then explore each sound's mouth shape and how it's made.
Round your lips into a tight circle. Lift the back of your tongue toward the soft palate and add voice.

Drop your jaw slightly with relaxed lips. Touch the tongue tip behind the bottom front teeth and arch the top-front toward the roof.

Same position as S, but add vocal cord vibration. Feel the buzz.

Touch the tip of your tongue to the roof of your mouth just behind your teeth. Add vocal cord vibration as you release.

Relax your lips, jaw, and tongue completely. Drop your jaw slightly and keep the tongue neutral.
The schwa before M disappears — M becomes the vowel of the syllable. Go straight from the previous consonant to M.

The textbook way isn't wrong — it's just not how anyone actually says it.
In "wisdom", the short unstressed vowel before "m" disappears — the schwa is absorbed and the "m" becomes the syllable nucleus on its own. Schwa is absorbed — consonant becomes the syllable nucleus.
Stress falls on the first syllable, not the others. Stretch WIHZ — keep everything else short and quick.
Don't pronounce the first syllable too fully. The unstressed syllable reduces to a schwa — the lazy "uh" sound — in casual speech.