With only one week left until the club starts, there were a few things I wanted to talk about that I think might help some folks relating to how to effectively approach your first manga! A lot of the ideas here are borrowed from discussions with @Christopherfritz, so if my rendition of certain statements is poor, I’m sure he’ll chime in with a much more eloquent version. 
Something that may be worth mentioning: While I don't know if it will show up in this manga for sure, it is a shounen manga, so it could come in handy: sometimes the furigana on a kanji is NOT how that kanji is actually read. For more information, click the arrow, since this turned into a larger section than I initially intended!
It is quite often the case that, if the furigana doesn’t directly match the kanji, it’s an attempt to insert some double-meaning and make a joke.
From “The Way of the Househusband”, in which 包丁, referring to a kitchen knife and which would usually be read as ほうちょう, is given the furigana ヤッパ, a slang-y term that is used by Yakuza members to describe a blade (like a weapon, not just a normal kitchen knife, generally). A lot of the humour of this manga is directly related to other characters misunderstanding this character because of how he speaks. The kanji is used to indicate to the reader that what he really means is a kitchen knife, but the furigana is what he says out loud, hence the concerned reaction of the gentleman to whom he is speaking.
More commonly in shounen manga, however, and something you’ll see in games quite often as well, is that something like attack/skill/technique/magic/etc names will be written as English words, or in katakana, and the kanji will be explaining the basic “idea” of what the attack actually represents. You’ll also often see this for organization names and the like, or unique in-universe titles/events.
From Tales of the Abyss, where 神託の盾 (which would be read: しんたくのたて if the proper furigana for those particular kanji were used “Shield of the Oracle”) is called オラクル or “Oracle”. (Incidentally, the group is called “Oracle Knights” in the English version of the game). As with the Househusband example, the furigana indicates what is being spoken by the character, and the kanji indicates to the audience what the actual meaning is.

From Cardcaptor Sakura. 封印解除, a made-up compound of the words 封印・解除 (actual furigana for those kanji: ふういん・かいじょ), given レリーズ as furigana, which would be the English word “release”.
Finally, I figured it might be helpful to include a list of the resources that I found absolutely invaluable when I first started out reading.
For unknown vocabulary, if it isn’t already in the vocabulary sheet, whether they be all-kana or kanji, I tend to use:
Jisho.org: Japanese Dictionary
It’s an intuitive interface, and you’ll find a lot there, though it doesn’t have everything, so keep that in mind! One major pro, though it doesn’t necessarily pertain to this manga, given that it has furigana, is there are “Search by Drawing” and “Search by Radical” options, so even without furigana, you should be able to find a kanji on that site!
Similarly:
英和辞典・和英辞典 - Weblio辞書
Is also a great source for finding words. It will also often give you a great list of example sentences, so you can see those words in context!
The downside is that the interface is primarily in Japanese, and if there’s a way to change that, I’ve not found it yet (also haven’t bothered to search around for it much), so it is a bit more difficult to use than Jisho, though the interface itself remains intuitive.
For looking up grammar, I’ll either literally just type the grammar point + grammar into google. (I.e., “てくれる grammar”), and look at those results, or I’ll consult a few different sites. It does sound like @gorbit99 is intending to include a grammar points sheet for this club, so definitely check that first! It will be curated to be sure that any vague grammar points are nailed down to their specific usage for the context, so that will help immensely!
Bunpro has a free grammar reference (the only paid portion of the program is the SRS, I believe), and has decent, concise explanations of many grammar points.
JLPT Sensei | Learn Japanese & Study for the JLPT (日本能力試験の勉強) is pretty decent at breaking down grammar points and giving example sentences, though much like Jisho, it doesn’t have everything! It does have a very intuitive interface, however.
Maggie Sensei is very good at breaking things down in a way that’s easy for me to understand. One of the big downsides, however, is that she is very much a “wall-of-text” explainer, and with all the different colors she uses to color-code grammar points, the site can quickly give you a bit of sensory overload. Ctrl+F is your best friend on her website, in my experience, though once you find what you’re looking for, she does a good job of breaking those points down.
Organic Japanese with Cure Dolly - YouTube If you aren’t much a fan of reading your grammar, and have better luck with videos, this channel comes highly recommended by a number of people. In my experience, she does a good job of making some particularly difficult points make sense, once she stops pontificating on how her method is the best method. I also have a hard time with the voice, but the downsides are definitely outweighed by the upsides of her explanations.
Japanese Language Stack Exchange For some of the more difficult grammar questions, sometimes the best results are in Q&A forums like stackexchange or HiNative! I always take these sites with a grain of salt, but they can be useful in finding some answers on the off-chance that nobody in the book club knows an answer for sure! (One of the fun things about Japanese is its ambiguity, after all, so even when you think you know something, sometimes it’s hard to be sure!)
Ichi Moe. It does a fairly decent job in breaking down sentences to individual grammar points and words, so that you can maybe piece together meaning from there. This is especially useful when you come across a sentence that you just can’t crack the logic behind, as it separates everything out in an easy-to-read manner, and also can often tell you if something is an idiom! It’s not perfect however, and especially once you hit more slang-y Japanese, or you put in names, it starts to not do the job as well. My suggestion for sentences with names: replace the name with a pronoun like 彼 or 彼女. This just helps the parser out a little bit and can give you a better result sometimes!
Finally, the weapon of last resort: a translator. Sometimes you might find that you have a very difficult time parsing something, and there’s just no way it’s making sense. In desperation, you turn to Google Translate. If you’re lucky, it spits out something comprehensible. More often than not, though, because Japanese is such a contextual language, it requires more context before it could possibly help you out. If you absolutely feel that you have to go to a translator, I would recommend DeepL Translate over Google Translate, hands-down.
I’m going to supplement this with this major warning:
It REALLY should be your weapon of last resort. You will almost always get a better answer talking it out with the book club, with people who are reading the same book as you, than from a translator which doesn’t have any context to the situation from which you are feeding it a sentence. This is especially the case in Japanese, which relies so heavily on context. The translator can break down to a few different scenarios:
- You put your sentence in, and the translator gives you an answer that makes sense, and it’s actually correct. (Best-case Scenario)
- You put your sentence in, and the translator gives you an answer that doesn’t make any sense, and it’s wrong. (Bad scenario, but not the worst-case)
- You put your sentence in, and the translator gives you answer that makes sense, but it’s WRONG. (Worst-case scenario)
The problem is, that if you are fairly early in your Japanese journey, you might not be able to differentiate between Scenario 1 and Scenario 3, and you’ll go on with a misunderstanding on how a phrase is used, or what it means. That’s why I say it’s absolutely a last resort, and should be avoided, but I’d rather give a link to a translator that’s a bit more accurate than Google to try and equip you a little bit better.