Standard British English makes a difference between a so‐called light and a dark /l/.
To make a light /l/, briefly touch the tip of the tongue up against the roof of the mouth (just behind the upper front teeth). The light /l/ is quick and is used when preceding an open vowel sound.
Examples :
lip light loss luck
The dark /l/ is formed in the same place in the mouth. However, because this sound is heavier and rounder, press the tongue up against the roof of the mouth but for slightly longer than you would for the light /l/. The dark /l/ is slightly longer and is used when the /l/ is not followed by a vowel (i.e., before a consonant or in final position of the word).
Examples :
milk pill people ball
lips lock lap land lie loom less link lead low
bill will fall wall file style mole role wild
mild