effective chess study plan
By playing the game= Will give you the most experience
Many games will not make you a better player. You have to analyze your games and fix your errors, otherwise you will learn bad habits.

A coach will help you make a study plan.
Without a coach, I'd say get one well regarded book on the endgame or a middle game idea (pawns, attacking, game collection, strategy etc). Read the book religiously and play in many tournaments. When you're done with the book, get a well regarded book on the other subject (middle or endgame) and read it thoroughly.
With your tournament games, analyze them and chat with stronger players about your games.
After that you should have a foundation of understanding, and can choose which areas need the most attention after that. Maybe openings, maybe more endgames, etc. But if you've never studied then in my opinion you first need some foundation. Even if the books cover some info you already know they can also help fill in any holes in your knowledge.

If you're really serious about training for 3hrs/day, you could use some of my suggestions for systematic training.