Although I can not come online it is as simple as this:
-Get very good armor (God Armor)
-Get a very good sword (God Sword)
-Stockpile health potions
-Stockpile Golden Apples
-Learn how to swap rapidly between items
-Stay away from anyone you have doubts about
~ @_Gimble_1.
This explains how to stay alive, but not how to kill.
If you want to actually kill people and get their items, you have to learn how to strafe and combo. I would teach you, since I've taught survivingsword, pyrotech, and some others, but I don't think I would have the time. Just look up some strafing and combo tutorials online, and remember, practice makes perfect. A trainer can only do so much until it's in the hands of the student.