"Be the type of painter you are, don't be like me. Take my work as references, paint and improve in your own styles."
So from here onwards, I've compiled few tips and named the types.
(Tips) Fine art and Chinese Calligraphy is an added advantage. You can find video in YouTube for extra info. Here I found one for you.
After you watch it, you will have ideas on painting free-hand any 40K/WHF icons/runes.