Short answer: Divide the song into logical sections, learn one section at a time, and practise the transitions between them.
Memorising an entire song can seem overwhelming if you try to learn it from beginning to end in one long sequence. The key is to recognise patterns and structure instead of trying to remember every individual note or chord.
Think in Patterns, Not Details
Most pop and rock songs are highly repetitive. A typical song may contain only two or three different chord progressions that repeat throughout the verses and chorus.
Instead of remembering dozens of individual chord changes, think of the song as a collection of repeating patterns. For example, you might remember that the verse repeats C–Am–F–G twice, while the chorus repeats F–G–C four times.
Reducing the song to a handful of musical patterns makes it much easier for your brain to remember.
Build the Song Backwards
After learning each section individually, begin connecting them together. One surprisingly effective method is to build the song from the end.
Start by mastering the final chorus. Then learn the section that comes before it and practise the transition into the chorus. Continue working backwards through the song.
This approach means you’re always playing towards a section you already know well, which builds confidence and helps prevent the song from falling apart near the end.