What Should I Do To Improve My Public Speaking Skill

Public speaking skill is the one of difficult subject for me because I must speak in english 100% pure english. Before i do public speaking, i did not realize that i have make a many mistake before this. My lecturer always give their opinion and comment about my weaknesses after i finish a public speaking presentation in class. I will improved myself to be a better than before, i take that comment from my lecturer because i know it give a positive impact to me. I also study the meaning of the word that i don't know by use a dictionary and the correct pronounciations so that i didn't repeat or make the same mistakes.