You need to be thorough with the basic tenses that we use in our day to day conversation .You need to know when to use which tense .That is more important.When you learn tenses, you automatically learn sentence framing too. Once you get an idea about the tenses, your confidence level will boost up to 50 %. Apart from tenses, when you learn the proper usages of pronouns, prepositions, conjunctions, punctuations and vocabulary, your confidence level will boost upto another 20%. Most important thing is practice. I usually give my students small topics or situation based conversation to improve their spoken skills once I am done with the grammar part. I have over 10 years of experience in teaching Spoken English. My students who were very basic in the beginning, showed drastic improvement in 50 hours.