HOW / WHAT

HOW

1.- Used for general opinion on something.

2.- Asking about general health.

3.- About preferences relating to food and drink.

EX:  How was your journey?

        How is your brother?

       How do you like your coffee?


WHAT

1.- When you are asking about general opinion with:

      What...... LIKE?

2.- For details with  What .... LIKE / HATE about...?
     
      EX: What do you like about the job? 

3.- About the consequenses  of something with WHAT IF...?
  
      EX: What if your plan doesn't work?

4.- About the naming of something in the question.

      EX: What is it called?