I think visiting an apiary and maybe even 'assisting' an experienced beek during an inspection is a must (doesn't really matter how - writing things down on the record sheet, if there is one, or holding the smoker, etc - anything is good to get into this stuff!) Unfortunately this does mean that starting on a whim at what is possibly the best time to start (i.e. during all the sales) is not necessarily a good idea. But do speak to a couple of people at your local association!
Another thing I personally found very useful is asking an experienced beek to pick up a bee and make it sting you in the arm (I did it twice). It is unfortunate for the bee, I know, but really useful for the person (irrespective of the result). Never mind the allergic reaction test, it's good to know first-hand how the stinger works over time, how to remove it, and whether you can stand the pain (personally, I couldn't stop smiling after removing the thing, - it didn't hurt nearly as much as I'd anticipated; a kind of liberation!). And if goes wrong in any way - better have any relevant advice sooner than later.
As per comments above: clothing, hair, food consumption, perfume, footwear, etc instructions are something you really ought to solicit before your visit. The person 'in charge' should be able to give you some basic instructions. It's not complicated at all, just ensures that you don't attract the bees to yourself too much, or annoy them before you get a chance to do anything. And if you happen to become a target, they won't find it easy to achieve retribution.
Kind regards,
Ana