<Source: Revised from Hougang Care Centre (Singapore mental rehab centre) Courses.>
To be confident in speaking in conversations, you must think you are worthy. Once the inner heart psychology is ok. Then speaking out is easy.
Start with a simple introduction. "Hi, good morning." or with stranger "hi, my name is cstan98."
Keep the conversation going. You can use free information (continue things other people talk out). You can use bridges (from one topic lead to another topic). You need to maintain eye contact with that person you are talking to or listening to, to sustain the conversation.
End with a simple ending. "Ok. Bye. I need to go." or "Nice talking to you. Bye."
The tone of your voice should be pleasant & not too harsh. Not too loud & not too soft.