How to do anthropics simply and practically.

If there are no issues of exact copies, or advanced decision theory, and the questions you’re asking aren’t weird, then use SIA. And by “use SIA”, I mean “ignore the definition of SIA, and just do a conventional Bayesian update on your own existence”. Infinite universes won’t be a problem (any more than they are with conventional probabilities). And this might not increase your expected population by much.