The "holding a beer" pose is difficult to master. You need to apply enough tension that there is clear muscular contraction and separation, but not so much that you EVER shake from effort, for then the illusion is lost.
Clothing choice is crucial too. No douchebag tight shirts. Casually tight, like "what can I do, the arm holes are too small" shirts.
You also need to make sure that your dominant arm always faces the honeys, which can be awkward if it has you facing a wall. Room location is likewise critical.