I did that last year for Scarlet Letter and their Eyes were Watching God
This year I'm doing it for Far from the Madding Crowd. My teacher called it a dialectical journal.
What was easiest for me with Scarlet Letter (I also did this with Their Eyes, but that book was much more fast paced, so it was easier) was to keep a composition notebook (or any paper) near you, with pen, and I'd just jot down the page number and the first few words of a quote that was interesting. I'd also usually put down a few (brief) thoughts on it's significance. Sticky notes could also be useful.
Every 40-60 pages or so, I'd sit down on my computer (I don't know if your assignment can be typed or not) and I'd type all the quotes I highlighted, and then typed my thoughts freestyle. Even if your assignment must be hand written, I'd type my ideas anyways, because they come out much faster and smoother. Then you can go back and edit them. The important thing is that you have the essence of what you want to say.
Honestly, starting off is the hardest part, especially with the more archaic classical novels. You just have to force yourself to sit down and get over the first chapter (or at least 10 pages). This, you have to find out how to do on your own. But once you get started, and into the habit of recording brief snippets of quotes and your own personal thoughts, you get much more involved in your reading, and it should become more interesting and easier. Aim to take note of something every few pages, even if they are tiny notes, to keep the flow going, or you might get into the habit of not doing it at all.
The point is to get close and personal with your novel, and "ask" it questions.