Dan Savage, Savage Love column 9/25/2008:

I order you to start having anal sex with your boyfriend immediately, ANAL. Tons of anal -- but without letting your boyfriend's cock come anywhere near your ass, 'kay?

In other words: yes to anal, no to dick. Think tongues, lubed-up fingers, very small toys and smooth, clean vibrators used non-insertively (which is fancy sex-advice talk for "lay the vibrator on your asshole, don't shove it the fuck in"), not dick. If you find that you enjoy other kinds of anal sex -- and you will -- your boyfriend's dick may start to look like a shiny new toy, or an enticing upgrade option, and not the intimidating asshammer that it appears to be now.

But for this to work, your boyfriend has to swear on a stack of Jack Morin's Anal and Pleasure & Healths that he will pleasure your ass, and get you off, without attempting to rush you or pressure you into dick-in-ass buttfucking until you decide you're ready.

I know that this isn't exactly to the point, but close enough. Basically, if you're excited enough, then his cock is going to feel better in your ass. I also recommend that he finger you vaginally or clitorally until you're very excited.