Hopefully, you already have a foundation based on prior classes that focused on reading, writing, listening and speaking.
For grammar support, English Grammar in Use by Murphy is excellent (and well-known). It is useful as a study book and as a reference for a quick check.
For speaking support, some people focus on grammar which usually inhibits natural, fluent conversation. I recommend working on fluency. Talk about life, starting with simple topics. When a person has a vocabulary of 1000 to 2000 common words, and a hundred hours of conversation practice, they can usually talk about past, present, and future events of interest to them.
For better grammar and vocabulary while speaking and writing, extensive reading (enjoyable books) and extensive listening (audiobooks) provide models of natural expressions. Gradually, a person "absorbs" the language. Without extensive reading and listening, most people think in their first language and translate to the target language, but the result is unnatural. With extensive reading and listening, people begin to think in the target language and to express themselves using modified versions of what they have absorbed.
Good luck!