This is the agenda I purchased this year (here).
I'm always color coding and in my last agenda I used the Papermate Profile 1.4 Ballpoint pens. This year though I decided to use the Staedtler Triplus Fineliner (you can also get these at Target but they are cheaper on amazon.) I also keep them in this super cute Tusk In Sun pencil case (they currently aren't selling any on amazon and that's were I got mine, but I found one here in First Impressions) from Lilly Pulitzer. It does look a little small, but it's also super spacious.
All I can really say for my tips is to color code! It's so much easier to write things down and looking at my monthly over view is so much easier because I know "Oh I have an orthodontist appointment because it green!" Or I have a test on Friday in English because it's pink and that means school.
In my week by week though I don't color code my classes like some people do because I find that I'll never grab for my pens to write stuff down. Since I always have my pencil with me I just write my class and the homework assignment. I can't show y'all that now though because I haven't started school yet.
That's mainly all I do in my agenda. It's pretty simple and easy. If y'all have any other tips or questions just let me know in the comments!