blow jobs?

okay so i've never given a blowjob. the guy i'm seeing always asks me to and i always say no.

1. i'm scared it's going to be bad. i've never given it but he's received it and i don't wanna give bad head

2. the idea of having a dick in my mouth kinda grosses me out?

3. i'm not sure what to do w my tongue and idk if i could fit all of it in my mouth

he goes down on me so i figure it's only fair, and also i wanna try it

if someone could give me some tips that'd be great 😅