Car Accident With 3 Different Citations.

I was in a car accident last night and I want to take legal action immediately. I was making a left turn at a green arrow and a truck came from the opposing lane going straight running a red and my front bumper hit his drivers side of the truck. they tested me for drinking and they didn't say I have a DUI or anything like that. I have three different citations and the cop said I'm at fault because I was making the left turn and should've seen incoming traffic. I don't know if the other person got a ticket and they are no seriously injuries and he was sent to the hospital to get checked up. Im taking this to court and I mailed the request to my district court. I want to know what I should say and not say when the court day comes and how I can gain the upper hand in court. I have a witness but they said they might testify but I can't rely too much on that because he said maybe and didn't see everything just as it happened and the aftermath. If you need more info to help or want to see images of the accident let me know. Thank you for any and all help.