Placing notes in the margins is a quick technique to help you get involved with what's happening in the LDS scriptures as you study them. Just write the main event in the margin next to the verse(s) that describes it. For example, when Nephi brakes his bow in 1 Nephi 16:18 write "Nephi Brakes Bow" in large letters in the margin. If you're doing the color coding method (Technique #2) you can write this in the topic's corresponding color or if you’re artistic you could draw a broken bow in your LDS scriptures.
I also like to keep track of who's speaking to whom so in the top margin, above the column I'm reading, I write the name of the speaker and put an arrow then write the name of the person/group being spoken to. For example, when an angle speaks to Nephi in 1 Nephi 14 I write: Angel -> Nephi. If there isn't a particular audience you can just write the speaker's name or put "me" or "us" as the receiver.
You can also keep track of who’s who in the Book of Mormon when there's more than one person with the same name, such as Nephi, Lehi, Helaman, Jacob, etc. When you come across the name of a new person look them up in the LDS Scripture Index. If there is more than one person with the same name you'll see a small number following each name along with a bit of info and corresponding references. Go back to your LDS scripture reading and write the number of the corresponding person after their name.
For example, when reading in 1 Nephi you come across Jacob. Look in the Index, under J, and you'll see four different Jacob's listed. Each has a number following the name along with some references. Which Jacob you've come across will depend upon where you're reading in 1 Nephi since both Jacob 1 and Jacob 2 are mentioned. If you're in 1 Ne 5:14 you would put a small one after Jacob's name, but in 1 Nephi 18:7 you would put a two.