If it were me, I would prefer to use rum as opposed to beer....most commercially produced american beer (Bud, Miller, etc, etc.) has little flavor, IMHO.
However, you can certainly use beer. I would recommend for a basic beer marinade:
A pint of beer...your choice
Some soy sauce, maybe a tablespoon or two
Some brown sugar -- a couple or three teaspoons or more if you think it needs it.
Minced (or powdered) garlic 1-2 teaspoons, depending on your preference.
You can also add other flavorings as you see fit.
Let the beef rest, refrigerated, in the marinade for at least an hour, up to 4-5 hours.
I would also add that this treatment will most benefit a cut of beef that is lean and loose grained...like say skirt, or flank. But you can certainly use any cut you choose. Good luck!