If you do not maintain the appropriate Arabic rules and grammar, your successful attempts to reach good Arabic fluency and a vast repertoire will not be useful. For example, if you address a man in the feminine form, it will be a big mistake.
Then you need to keep your conjugation skills as good as possible to include the gender nouns, adjectives, and the corresponding verb forms, etc. There is an Arabic Grammar: A Learner’s Guide, an excellent resource for studying Arabic grammar. It teaches you practical Arabic grammar progressively and logically.
Thus, it is more important to obtain a good command of grammatical rules and syntax in Arabic.