How to use the online timer
Thirty minutes suits the guitar particularly well because so much of the early work is physical: chord shapes, changes between them, and fingertips that need time to toughen up. Beyond about half an hour a beginner's hand stops learning and starts merely hurting, and coming back tomorrow does more than pushing through today ever will.
Tune it before starting — every session, without exception, since the humidity here shifts tuning noticeably between one evening and the next. Spend the bulk of the time on changes between two chords rather than strumming ones you already know. The count runs in this browser tab, so leave the page open beside you rather than closing it when the phone lights up.
Use a metronome even when it is uncomfortable, and set it slower than feels reasonable. A chord change made cleanly at sixty beats per minute becomes a change at a hundred within weeks; a change made scrappily at a hundred stays scrappy indefinitely. Strings also go dull faster in a humid climate, and a fresh set often solves a problem that felt like a playing one.
Common questions
Why does it go out of tune between sessions?
Humidity and temperature both move the neck and the strings, and the swings here are noticeable. Tuning at the start of every session, without exception, is the simplest fix.
My fingertips hurt. Should I push through?
Not much past half an hour early on. The skin needs time to toughen, and coming back tomorrow builds it faster than a long session that leaves you avoiding the guitar for three days.