According, to latest changes in MHT CET it's level is raised to JEE Main.

Class 11th holds 20% weigtage in the exam and class 12th holds 80% weightage in the exam. So, you should prepare accordingly.

There will be no negative marking as well.

You should refer your text books first to clear your concepts.

After, your textbook you can refer to MTG, Marvel, Pradnya and Disha books.

Make sure you solve complete mock test series to know where you stand among other competitors, So, that you can analyze and improve your performance.

Good Luck!!