Best way to protect and strengthen voice outside of warming up and training

ive been warming up nd doing lessons, at the moment its been really cold so i just want to know if theres any way to stengthen voice and protect and also if theres anything i should avoid that damages my voice

Straw singing is excellent for strengthening the voice in a safe, gentle way. Please see below for a few resources on vocal health:

Article on preventing vocal injury & maintaining vocal health

Hour-long lesson on strain, pain & vocal health