First time doing anal probably tomorrow

I'm sure there is going to be rimming and fingering and all that involved. I'm a little self-soncious about people eating my ass, but I'll give it a shot. I just want to avoid anything dirty like him fingering me and having a dirty finger after.... It's more than 24 hours from now haha. I can eat very little the day leading up to it if I need to. I just need advice from you guys on how to avoid a mess.TIA