I’m a high school dropout who learned how to learn way too late:
No distractions. None. No background music, and nobody else in the room watching TV with the sound off or reading the newspaper or anything else that “Isn’t distracting because it’s quiet” (Yes dad, that means you), and absolutely not pets allowed.
Also, make sure you’re done with bathroom and food beforehand. Bring water and maybe even some snacks to ensure that you have no excuses.
And if it’s a boring subject, bring an egg timer: 20 minute sessions, 3 minute breaks, on the mark. Ticking timers/clocks should be cast into the flames of hell.

I’m doing fine today, but it took me until my late 20s to figure out this and myself.