How to get to diamond?

Currently I am Plat IV and I need some general tips on how to get diamond by the end of the season. What are some strong picks right now? What is the difference between diamond players and platinum players? Is it worth it to play normal games to practice mechanics? Any help would be appreciated. I know that game knowledge/decision making and a good attitude are very vital to climbing the ladder. I'm wondering if there is anything else I can do to carry.