You'll almost never hear people use the word "apprise," and if you do hear it, it will usually be in the passive voice: "he was apprised of the fact that..." It's really not a very common word, though. Unless you need to know it for an exam, I wouldn't worry too much about it. "Appraise" is much more common, so it might be best to simply focus on learning "appraise." If you need a way to memorize which one is which, I guess maybe you could think of the extra letter in "appraise" (the second "a") as adding something "more," or "extra," to the word. When you "appraise" something, you estimate its value, so maybe you can think of the word "appraise" as having extra substance/value, compared to the word "apprise," which has only one "a." Someone else might have a better idea, but that was my first thought!

Sorry, I can’t think of any “tricks” for this one. Just practice using the words in sentences (out loud) where the meaning is crystal clear in context, and make absolutely sure your pronunciation is spot on accurate. Actually, make sure your pronunciation is perfect *before* making the sentences. Good luck!

There are several viable options for vocabulary acquisition. You might want to try something implementing spaced repetition systems (SRS), mnenonics, or experiment with something like the gold list method. I am a huge advocate of SRS, so this would be my personal recommendation. All the best!