Learning tunes and remembering them comes easier with a system to "mark up" your music.
When I begin work on a new piece of music, I start with (at least) two copies of the music. The master copy stays clean and unmarked, and acts as a backup for my files. The additional copies get lots of notes, comments and markings added over time.
First, it’s critical for my memorization of a tune to break the piece into its phrasing. For example, in "The Siege of Delhi," the ending phrase (the last two measures) is repeated in each part. Master these two measures and you’ve got 25% of the tune. Likewise, the first two bars of each part are repeated on the second line of that part. So I use a set of colored highlighters (thanks Dollar Store!) and choose a different color to mark each repeated phrase. This gives me a great indication of how many two bar phrases I actually need to learn. Sometimes, there is a repeating phrase except for a note or two—usually I will mark them in the same color but circle the areas of difference.
Next, after playing through the tune, I’ll circle particular areas of concern. In "Siege" it might be the A–short B–grip to C, which is played around 26 times in the tune, or it might be the E–C–B shake in the first line ending of each part. We all have our personal points of concern. Once these are identified, you can come to the Dojo U and find great classes and exercises to help resolve these issues. (See below.)
Often, with my marches I’ll end up marking up the beat. In a 2/4 march, you can mark the first beat in a measure with an L for left, and the second beat in a measure with an R for right. This is what I've found makes the most sense to me.
When I’ve got the music prepped this way, my practices are more effective and focused and my memorization seems to happen much quicker. This works for me. But developing your own system of marking up music, one that makes sense to you, will lead to more effective practice and better learning.