How to study and improve
Does wiki need this page? seems a lot like http://senseis.xmp.net/?HowAndWhatToStudy
HowToStudyAndImprove How to study and improve at Go.
If you are a ddk, then read Tesuji, Attack and defence and Lessons in the fundamentals of go, in this order and keep repeating them many times! You must play a lot of games and also must try to apply what you learn from these books in your games! This should take you to 5 kyu in less than 1 year!
If you are already sdk, then solve as many tsumego problems as you can for at least 1 hour a day! Your core Go strength comes from tactics, like in Chess. With a strong tactical foundation, you can then easily see weak groups and profit by attacking them, you'll also easily follow joseki variations and quickly understand and follow how joseki mistakes are punished. Then study modern professional games to learn modern joseki, strategy and direction of play, but you can brute force your way to 1d by just solving tsumego and learn the rest through osmosis via playing and reviewing your own games. The best go players have frightening calculation abilities, and when you have that under your belt, you tend to send your opponent reeling, especially during tournaments.
You can print Tsumego for free at http://tsumego.tasuki.org/ Though I think you should ignore Igo Hatsuyo-ron and do https://vk.com/doc11528726_363286842?hash=b66e99699919b5ab6d&dl=aca9f63fdc6e54917c (Guanzi Pu) instead! This progression is all you need IMO, just keep repeating a collection until it "feels" easy, then move to the next, harder one. Once Guanzi Pu feels easy, you should be a kgs 5d(at least)!
You can print professional game records for free at http://gokifu.com/. How to study pro games: The first and second time, just play according to the diagram. The third time you play the game, start actively thinking about reasons and alternatives for every move. The reason for doing it this way is simple. If you think about the game from the very first time you play it through, you will use your own knowledge as a reference point for understanding the game, and your knowledge is weak...
Playing is certainly one of the most efficient ways to improve. In addition, reviewing your games can help you to learn from your mistakes. You may consider to contact a teacher, who can help you to point out your mistakes. But you can also use software to review your games with the help of the calculations of bots. Lizzie is a tool which can help you to review your games in this manner. If you prefer not to install any software, you can use ZBaduk to review your games, which performs its calculations online without using the resources of your computer. You can also use zbaduk to review your games on your smartphone or tablet.