I would recommend 'The Adventures of Huckleberry Finn' by Mark Twain. It contains a variety of sentence types and colloquial language. You can learn about verb tenses, subject - verb agreement, and how grammar functions in a more casual, yet still grammatically correct, style of writing. It also helps with understanding grammar in dialogue.
For English grammar improvement, 'Wuthering Heights' by Emily Bronte is a good choice. The complex sentence structures in this novel can really test and enhance your understanding of grammar rules. For example, the use of subordinate clauses is abundant, which helps you get a better grip on how to construct more elaborate sentences.
One great novel is 'The Great Gatsby' by F. Scott Fitzgerald. The language used is rich and descriptive. It has a lot of beautiful sentences and a wide range of vocabulary. Reading it can expose you to different sentence structures, which is very helpful for English learners.
'Alice's Adventures in Wonderland' by Lewis Carroll. It is full of unique and imaginative language. The grammar used is not overly complicated but is very precise. This makes it great for those who are starting to focus on grammar. You can learn basic grammar rules like noun - verb agreement and the proper use of plurals while enjoying the fantastical story.
Using grammar apps can be very helpful. There are many apps available that offer grammar exercises and explanations. They are convenient as you can practice anywhere, anytime.
Using grammar exercise books is also effective. You can find many of them online or in bookstores. Do the exercises regularly and check your answers carefully to correct your mistakes.
Watching English movies with subtitles is also useful. You can listen to the natural flow of language and then check the subtitles to see how the grammar is used. It's a more engaging way compared to just studying from a grammar book.
Taking an English grammar course can be very helpful. In a course, you'll have a structured way to learn grammar rules, and you'll get feedback from a teacher or instructor. Also, using grammar apps on your phone is convenient. These apps usually have quizzes and explanations to help you understand different grammar points.