Here is a suggested marking symbol for angel. It’s the letter “A” with the middle line drawn to resemble wings. I use either a yellow or gold gel pen. But don’t forget that you can use any symbol or color you want when marking key words in your Bible. Making a pretty picture isn’t the goal. The goal is to dig out the truth of God’s Word for yourself.
Don’t know what a key word is? Check out this free introduction to Inductive Bible Study. Put down books about the Bible and start studying the Bible itself. There is nothing wrong with using other books as study tools such as commentaries or Bible dictionaries. But so often we use those to replace our own personal observation of the Word. First try digging out every little nugget of truth out of a passage by thoroughly observing the text before you turn to those other study tools.
Here’s a suggested symbol for the word reconcile.