Getting better at Go requires that the game is played, and preferably reviewed. But when a match isn’t possible due to time or lack of an opponent, studying life and death problems can very helpful. I recommend starting with the basics, like low level problems. Some joseki and fuseki problems are ok too, but life and death, in my opinion, will serve you better. My first introduction to life and death was a book. That book is: “The Elementary Go Series, Volume 4 Life and Death” This book is a good start, but where to go from here. There are many books on life and death, and some additional ones can be recommended if you ask.
As mentioned in the THANK YOU post on the home page, Tim Kington wrote a program called GoGrinder. This program is excellent for life and death problems, and the incorrect buzzer is a good deterrent for making a guess rather that reading the scenario out. You can even load problems from a book into the program. GoGrinder is available for android devices from the “Play Store”, on any computer that runs java linked from GoGrinder’s homepage, and on older iPhones. Unfortunately, Tim discontinued updating for iphone devices early on, but it will still run on older iPhones.
Move to harder and harder life and death problems as you get better, but go back to the easier problems on occasion too. Reading skill can be developed by the hardest problems you can manage, but the easier problems still help to make flaws instantly recognizable. In addition, easy life and death problems are built on common shapes that are exploited. Harder life and death problems will still fall back on these shapes, but the situation will be less developed and harder to see.
I wish you the best of luck with you Go journey, and as always, feel free to contact me at firstname.lastname@example.org