Pizzicato
A brief discussion regarding pizzicato
The middle finger offers much better flexibility for playing most pizzicato. Remember that the string works best when pulled side to side (like the bow does) and not up and down (unless you are supposed to make a “Bartok pizz” -type sound). Having your right hand supinated (rotated clockwise) gives you the most natural approach as the finger is designed to move most easily in this direction (up and down- like playing the piano, but side to side when rotated). This also allows you to hold the bow securely (but easily) with the other fingers while playing pizz.
Do NOT play near the bridge, the string is least flexible and responsive there, and it sounds ugly. The most flexibility of the string is at the midpoint, but that point changes depending on where your left fingers are on the string. For this reason, the easiest place is a few inches up the fingerboard with your thumb touching the side of the fingerboard for stability. Look for videos of jazz bass players like Ray Brown, they are the best models to emulate for pizz for cellists.
An important consideration is the regular practice of pizz so that our right hand fingertips and thumb are able to pizz without discomfort. It takes a while to build up the calluses that protect our skin from the friction endemic to playing pizz. When I was playing in a piano trio for many years, anytime we would program the Shostakovich Piano Trio in E minor, I would practice playing fortissimo 4 note chords with the thumb daily for weeks in advance, otherwise I could not perform this work without great pain. There are many pieces in the larger repertoire for cello for which we must be prepared to play pizz without pain.