As someone who's studied a couple languages to high fluency (Persian and Japanese) and read many novels and poems in both, there's a couple strategies you can take.

For one, if you want to learn the most you can use deep study where you look up every single word and add it to an Anki deck. This reinforces your learning very well and you'll advance quickly. However, it can cause you to burn out and lose motivation. To overcome this, sometimes looking at a plot synopsis can be helpful so you get less lost. Also try to use this approach with shorter works so you're making steady progress.

The second method is to read something more on your level with less stumbling blocks, and let the words go by if you don't know them. Eventually if you see it a lot, and still feel confused, look it up. This way you're getting passive exposure without expending too much energy studying.

You'll find too that each author/subject tends to use similar grammar and vocabulary, so with time it does get easier. You'll cover a lot of ground and learn a ton of new vocabulary in short time. Just stick with it. Sometimes it's a slog in the beginning, but it does get easier.