How to Prepare for a State Test, WIDA, Exam, Standardized Test, Etc.

It's hard to know what to suggest without knowing your students more personally but I've included some ideas below:

1. You can't really cram for a test like these but you can practice in the same way that the test is set up with similar types of texts and writing prompts. Students will need to read texts, show comprehension of those texts, and write reasonable, grammatically-correct responses to comprehension or essay questions.
2. I would start having students do just that. Read a text that challenges them. Use techniques like annotation to understand what the text is saying. Here is another guide with some ideas for how to organize a lesson like this.
3. Then write an organized response using something like the R.A.C.E.S. strategy. I wouldn't focus so much on grammar or spelling at this point, but more on organizing thoughts into a way that a reader can understand the main points of what they are saying.
4. You can make the texts short enough that you can go through these steps every class or every two classes. The routine and repetition of this should build a lot more confidence for the actual test.