First Time Anal Advice

So

I’ve never tried anal before but have been interested by the idea of it but felt close enough with somebody to try,

My partner and I are long distance but I’ve never felt to trusting and comfortable around anybody else. We are both very interested in trying anal.

He’s put a finger in and eaten my ass previously but I’m scared of anal for one reason and one reason only. Poo.

That’s right, poo. I’m scared that I’ll get my poo on him, which I know he wouldn’t care about but I would

Any tips to avoid this or even general first time advice