Hey,
I have been instructed to strengthen my lower lip by a very good flute player! The pieces i'm playing are way beyond my development, as I haven't been playing that long. I can play the pieces tonguing and fingers, it's just tone and smoothness!
Anyone know how to do this?
Pyface

why do you want to strengthen your lower lip??? you are not playing clarinet or saxophone...

if you are using old type embouchure like the smiley embouchure , you should strengthen both lips.

if you are using the new type embouchure like the sad face embouchure , your lower lip should be fully relaxed.

if you are using the new type natural embouchure , both your lips should be half relaxed.

You are a beginner, you should learn how to relax instread of stress your lips, becoz once your lips are stressed, your tone will become very thin and ugly for the rest of your life.