Sticking to the very basics, you must realize that wine knowledge at its core is not important to surviving on the job. The first thing to focus on, is which wines the establishment carries. Unfortunately, this can be difficult when dealing with huge wine lists. If you're in a restaurant with thirty, or maybe even fifty... or perhaps they have a whole cellar dedicated to wine, you'd never be expected to know about all of them. A good practice when starting out is to look at the wine list, and pick out a couple of the cheapest wines for the reds and whites. Wines on the cheaper end of the spectrum are what get ordered the most, so knowing these wines is important. As for those people going into interviews, do whatever you can to dig up a wine list. If its not on their website try to get a look at it when you're dropping off your résumé.
Continuing to study the wine list can reveal a lot of different things. Firstly, it can give you information overload. To avoid that, take a step back and consider some other things. Is the wine list separated into flavour categories, such as spicy, bold, or oak? Is it separated by sweet and dry? Are there a lot of say, Cabernet Sauvignons and Chardonnays, but only one or two of the other types of wine? Usually these things are pointers for gathering more information. If there are flavour categories, it could be a good practice to pick one wine out of each category, and the same can be said for wine lists divided by a sweetness scale. And of course, having a lot of cabs on the menu might tell you that a lot of people order cabs.
So now that you've picked out which wines you're going to learn about, how do you learn about them? Well my friend, every wine has its own story, and its own unique character, luckily for you, it's written on the bottles of most wines, and for those it isn't there's Wikipedia. That's right! You don't have to take advanced wine tasting classes to learn all of this information, because wine knowledge has to start off with the basics of product knowledge. And of course, that information can be found on the bottle!
But now there's another problem. If you've accumulated a list of eight to twelve wines, remembering their names can be hard enough. How can you memorize all of the information on the bottle? I understand that the majority of you don't have a freakishly good memory. It seems I was blessed with a photographic memory, but even still I had difficulty remembering everything about my store's products when I first started. I'll urge you again to take a step back and look at the 'smaller' picture. For starters. If eight to twelve wines are too difficult to remember then start with four, and make a pledge to add one more wine to that list of products you know, until you find that you can suggest a wine for every meal and occasion. You don't have to be the most knowledgeable on your first day, but aim to progress gradually.
As for what to remember, just note that memorization should not be done verbatim. The four things you should know without question are what the brand name are, what type of wine it is, whether its white or red, and where its from. These are all easy questions, and the first three should be known just from reading the wine list. Where its from, may or may not be on the wine list, but is easy enough to learn by looking at the bottle. Furthermore, you might notice that a lot of old world wines are categorized by what country they're from; id est you find most Rieslings in Germany, most Chiantis come from Italy. New world wines can be more tricky to make this sort of breakthrough with, but nevertheless you'll find that California is known for its Chardonnay, while Argentina is a country of Malbec. This is a good discovery to make when you're trying to transition to that place of having strong wine knowledge.
You can learn a lot more from reading the bottle though. You can learn the story behind the name; always a favourite for guests, which shows you know your stuff. You can also learn the flavours and aromas. With concern to your tasting palette, you may find that all you have to do is know one or two flavours found in the wine in order to sell it. You'll also find pairing suggestions. This is another easy area, as you can often divide things by whether they should be paired with red meat and desert, or everything else. You CAN go the extra step and find more specific pairings, and in fact that's suggested, but if you have trouble, try to stick to either pairing heavy or light wines with heavy or light meals.
What you should try to remember is that its easier to memorize things when you're starting off with a simple foundation. Wine knowledge is an overwhelming concept for a newbie to tackle. The secret to doing well - as with many things - is to simplify.