I am sure that you have already know how to express your thoughts in many ways, because you can express your thoughts by writing.  For spoken English, my experience told me that my spoken English is needed to be confirm. If one of my expressions has been confirmed by anyway, then this expression impressed me a lot, and I can use it in my spoken English confidently. There are several ways to confirm your spoken English. Which I have tried before.

1. Ask my teachers help me. Once my teacher correct my expression, then it will impress me. Notice only take conversations with my teachers won't help me in spoken English. During the conversations, the teachers can still understand me even I speak English incorrectly. If my teacher cannot correct me, I just enforce my wrong expressions time and time again. So teachers' corrections are very important, in my opinion, no corrections, no improvement in spoken English during the conversations(absolutely I can practice my listening skills ).

2. Pick up some expressions from TV shows. If I sound an expression on TV shows, I will use it without doubt. 

3. I read some business English, there are many useful expressions which used in workplace.

My opinion is, when you are not sure about your expressions, you need to stop here and find some ways to confirm, and not just let them go. Otherwise, you just enforce some wrong expressions time and time again.