To effectively practice a skill without a teacher it helps to keep in mind three Fs-Focus. Feedback. Fix it.
Quote
To effectively practice a skill without a teacher, it helps to keep in mind three Fs: Focus. Feedback. Fix it. Break the skill down into components that you can do repeatedly and analyze effectively, determine your weaknesses, and figure out ways to address them.
Author
Anders Ericasson
Reference
Peak - Secrets from the New Science of Expertise - Anders Ericsson