Use them sparingly at their most effective ranges. Due to the range you are put at the most worrisome thing is having a poke focused and getting crumpled. Learning to punish focus is important.
st.hp is actually incredibly safe because it doesn’t normally hit on the first active frame.
I like to use st.mp, then either cr.hp or cr.mp after to catch people trying to hit buttons.
st.hk is not a poke. It is used for AA and combos and sometimes frame traps. But there is no real way to poke with it, the range is terrible. It’s decent after a blocked cr.lk or electricity though.
cr.hk is like any other sweep. It’s best for whiff punishing, option selecting, and combos(fa lvl 2 backdash, hop, sweep is good). Certain characters like Fei can punish sweep whenever they block it, so you don’t want to use it in footsies, but the characters who can’t, you can use it as a poke more often.