Voice improvement help!?

ok so i need help with improving my voice (even just a little) things like tone and pitch. Im going to be recording in my uncles studio in a few weeks (just for fun, nothing huge) and i wanna sound decent. I'm recording with my best friend who is absolutely amazing at singing, and i dont wanna sound bad in front of her. (no, i usually not sing in front of people, but ive somewhat gotten over it lately) I used to be in show choir several years ago but havent sang a lot since, so i was wondering if anyone could give me some tips!! Vocal warm ups and stuff, anything helps :)))