Press your lips together. Air flows through your nose. Vocal cords vibrate.

Americans pronounce midfield as MIHD-feeld (/ˈmɪdˌfild/). The L in "midfield" is a dark L — the back of the tongue rises toward the soft palate, adding a small "uh" quality before the L. This is called the Dark L vs Light L, and it's one of the defining features of casual American English. It comes out as MIHD·FEELD. Stress falls on the first syllable — keep everything else short and quick. You'll hear it in sentences like "He wears jersey number ten and plays in the midfield".
Record yourself saying "midfield" 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. Air flows through your nose. Vocal cords vibrate.

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

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

Lift your bottom lip to touch the very bottom of your top front teeth. Blow air through this contact point without voicing.

Pull the corners of your lips back slightly. Arch the middle-front of your tongue high toward the roof of the mouth.

Keep the tongue tip down and pull the back of the tongue up toward the throat. The 'dark' sound comes from the back.

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

The textbook way isn't wrong — it's just not how anyone actually says it.
The L in "midfield" is a dark L — the back of the tongue rises toward the soft palate, adding a small "uh" quality before the L. Dark L adds a small schwa-like "uh" before the L. The back of the tongue lifts toward the soft palate.
In "midfield", the "d" is not released — the articulators get into position but hold without the burst of air. Air stops but there's no release burst — the articulators hold position.
Stress falls on the first syllable, not the others. Stretch MIHD — keep everything else short and quick.