I have been playing chess (sometimes a lot, sometimes none) for a very long time. I want to become an international master in 4 years, or have a rating of 2000. I am 15 right now and have a rating of 1300. What is the best way to spend 30 minutes a day doing "chess stuff" to maximize improvement? Thanks
In theory, you need 10,000 hours of (good) study to master any subject. A four year goal would require about seven hours per day. GM Donaldson, quoted some time ago, studies five hours a day before a tournament just to stay at his level.
The most effective improvement is in tactics. Tactics is said to be 99% of chess (various authors) and most games are decided by tactics.
Capablanca is often quoted as saying that you should study the endgame first, but a basic knowledge (pawn endgames, simple rook endgames, and mates) should provide you with enough skill to achieve you goal.
The opening should only be deep enough for you to get to a playable middlegame. You should understand the moves behind three openings (one as white, and one against both common white openings) along with common middlegame strategies.
Positional chess is the most difficult element to master. Although Nimosvitch provides the basics definitions in My System, it's still hard for most people to understand. However, without this knowledge, at the higher level, you'll lose game after game without understanding why.