(Note: The posts on this blog won't be in a specific sequence; some posts will be for beginning learners, while others will be for more experienced ones, though I hope that even if a particular post isn't at the level where you currently are, you can still get something useful from it.)
When players start studying the bingos (or bonuses, outside North America) - the seven- and eight-letter words - they're presented with learning two skills at once. The first is knowing that a word is valid and being able to recall it, particularly when the word is obscure, and the second is being able to look at a tricky string of letters like AEFILNRU and find the real word or words in those letters. (That's a quiz: I'll give the answer at the bottom of the post.) This is all true for the shorter words as well, but the bingos are where you'll rely most on your unscrambling abilities. So you'll need to study bingos in a way that not only teaches you the words, but also builds that unscrambling ability - because the sooner you build that ability, the quicker you can add bingos to your arsenal.
I've met a number of newer word learners who maybe started their bingo study by learning the seven-letter words formed by adding a letter to six-letter bingo stems like SATIRE or RETINA, and they've gotten a decent way into that. But if I ask them about eights, they say they're waiting to get a good number of sevens under their belt before tackling the eights. That sounds sensible: when we learn the shorter words, we typically do the threes, then the fours, then the fives.
However, for bingos, I think there's a better way to fly. When I started practicing bingos, I noticed pretty quickly that eights were a good deal tougher than sevens to unscramble - I was much slower on eights and got fewer of them right. That one extra letter adds a lot more possibilities for your brain to sort through, and if you don't have that unscrambling practice under your belt, it can be slow going.
This is why I recommend that new bingo learners actually spend MORE time on eights than on sevens, maybe a 60/40 or 65/35 ratio in favor of eights. Sevens and eights are, in general, about equally important to learn, but if you do more eights to start with, you'll build those unscrambling muscles quicker, which will also help a lot when you work on the sevens. It's like adding a little more weight to the bar when you're working out; the workout will be a little tougher, but the long-term payoff is well worth it.
However, remember what I said about making the learning fun? If you're not that good at anagramming yet and you take on a big pile of high-probability eights, you might find yourself getting pretty frustrated with your low solving percentage and lack of speed. That's not fun. So I recommend two things to help you lessen that frustration and build more momentum.
First, when you study high-probability eights initially, don't just take on everything in the top 1000. Instead, study only those alphagrams in the top 1000 that have one and only one solution. (Zyzzyva allows you to search for those easily, and I'll post a list of these here today or tomorrow when I get time.) So instead of annoying yourself by not remembering and finding every last one of the zillion words in ACEINRST, you can just concern yourself with remembering and finding one solution at a time. That way you'll move through the words faster and have a better flow. Once you get a bunch of these words learned and become a little more comfortable with solving eights, you can go back and add the ones with multiple answers.
Second, when you study eights, don't limit yourself to just the highest-probability eights. Here's why: high-probability words, which are mostly collections of one-point tiles, are generally much harder to anagram than lower-probability words are. Lower-probability words tend to have high-point tiles like K or Q or W or Z in them, and those letters can simplify your unscrambling process a lot, since there are fewer ways those letters can appear in words. With high-probability words, you don't have that help. (For example: The low-prob CCEHIKN is much easier to solve than the high-prob ILNORST, though they're both commonly known words.) So here's how you ease your burden a little: when studying eights, do the high-probability stuff most of the time, because those words will help you the most in the game, but mix in maybe 25% of the time doing a lower probability range of eights, something like 15000-16000. It'll expose you to a more varied and interesting set of words (at least in my opinion) that won't be quite as hard to unscramble as the high-prob words are, and again, you'll have more fun and get into the flow easier. And if you happen to unleash one of those obscure lower-probability beauties in a game, all the better!
These two tips are just as useful when learning sevens, too.
* Quiz answer: AEFILNRU is FRAULEIN.