When i’m reading books from bookclub i’m not sure if i should look up words with sheet or try to search them myself and try to guess correct meaning. I think i will learn more by doing it myself, it’s hard though to stay motivated.
What is your approach to reading?
Inferring from context and getting generally independent about how you learn new words certainly isn’t a bad idea, but reading between the lines, I’m assuming that you are relatively early in the learning to read process. I don’t need to tell you how hard that is I’m sure, heh. For that reason alone, I’d recommend giving yourself all the help you need to smooth things out. By all means, experiment with anything, but since you say it’s harder to find motivation – I can promise you the spreadsheets won’t sabotage you. Personally, I read plenty of volumes of manga with spreadsheets guiding me through every fifth word before inching my way to more self-directed reading and lookups, once the surrounding challenges compounding with unknown words slowly eased.
It’s all up to personal preference. Sometimes we prioritize speed and wanting to read because we’re very interested in the content (and having to look up every single word ourselves is time consuming and can sometimes kill the enjoyment of reading).
You can also be selective of which words to look up. For example, if you get the general idea of the sentence or passage, it’s not necessary to know the exact translation in your native language. I do look up every single word if I’m reading something seriously (I intend to continue the series - it’s likely you’ll encounter many words multiple times and they’re likely to stick permanently). I also teach English to Japanese speakers, and I’m so used to using Japanese in my daily life that I forget the English equivalent. 
Although making my own vocab lists has been helpful, I’ve started experimenting with writing them out vs. typing them since it also helps me practice writing the kanji and making it more likely to stay in my brain, specifically my muscle memory.
Of course, this is even more time consuming than typing, but I prefer it over typing on my phone (which the baby likes to swipe at) and the laptop (my preference) is hard to use when same baby gets cranky at the loud typing sound of the keyboard.
So yeah, try different methods out for yourself and see which you prefer. 
As someone who was in a similar situation to you a couple of years ago and decided I would learn better by looking up anything that I didn’t know myself, let me tell you, it took hours each week and I still struggled because the other problem was getting my head around the grammar I didn’t know.
It’s about finding the right balance between challenging yourself and not making it so difficult that you get burned out, so I’d say use the vocab sheets if you need to if it keeps you reading along with the group for the duration.
All the best 
My two cents 
If your goal is to read: use the vocab lists so that you enjoy the book! You’ll get plenty of reading exercise on all of the words and grammar you can recognise.
If your goal is to memorise new vocab: whether you look it up, or you read it from a list, you won’t learn that word. You have to put it somewhere you’ll see it again… luckily, books usually repeat many words! Since the method doesn’t matter, I would choose the list as it saves time (and make cards of the vocab you keep having to look up grr)
If your goal is to challenge yourself: now is when I confess that I don’t often use vocab sheets Because I love having to guess what the word might be 500 times or having to write the radicals into my dictionary! I don’t care how long it takes, it’s about the journey. But I first read through a large chunk, highlighting the words I don’t know along the way, then going back a second time to look them up. Otherwise, I loose motivation and stop reading entirely.
Last advice: Play it by ear! How do you feel today, or at this moment? You don’t have to choose just one way and stick with it, you can do any combo at anytime depending on your motivation/mood/point in that book.
P.S. Wishing you luck in your reading journey! Will be cheering for you, and would love to see you update us after you found a way that suits you 
I try to get the words I don’t know from context.
Sometimes it works, sometimes it doesn’t. It’s easy to find out if you’re active in the threads.
For this, you need to know like 90% of the words so you don’t overwhelm yourself with blocks of text you don’t understand.
Otherwise, you should start studying common vocabulary if you’re planning to read books, imo. 
Or you could do both and try to guess them from context, then if you don’t get it, or think you already do, check the sheet afterwards.
Personally I don’t use vocab sheets for the same reason I don’t like using Google Translate (the only available pop-up “dictionary” on Android): they tend to give only one translation for any given word. Looking up that same word in the dictionary gives me a multitude of definitions, and I find it easier to get to the correct nuance that way.
That said, this is all down to personal preferences, and I don’t think anything you choose to do will harm your learning. I believe I am in the minority, but I never bother with vocabulary when I read, never care how many words I don’t know (always lots). Vocabulary can’t stop you understanding, because you can always look it up. It’s grammar that’s the main obstacle, and a general feel for the language that you only get by reading/listening a lot. The most difficult sentences I encountered all had completely known, simple vocabulary, yet it was still hard to figure out what they meant.
My thought, is
This is to enjoy the benefit of book clubs.
However, for reading by yourself, it is better to know a lot vocab first, the realize the nuance in context. Look up some vocabularies is OK, but probably not to focus on them too much.
That is, I still think it might be better to read more than once.
Well, when it comes to words knowledge. I kinda know a lot by ear (i listened of japanese from childhood) and when it comes to communication etc. on japanese lessons with native i don’t have much trouble with communication. I’m lost because in Yoru Cafe (nice example as i’m reading it right now) i see a lot of words that are synonims to words that i know. I planned to add all unknown words to houhou srs to learn them, but i’m kinda afraid that this will result rather with burning out instead of becoming more literate.
I would definitely be careful with this, yeah. It’s possible to add all unknown words to SRS, but doing so would probably force you to read pretty slowly, because you wouldn’t want to overdo it.
Also, for me at least, it’s a lot easier to learn a word via SRS if I know the kanji in it already. If I don’t, it takes me way more effort to learn. I tried adding everything new to Anki when I initially started reading manga, but I immediately realized I couldn’t keep it up, because there were just far too many unknown words, and I didn’t even have the mnemonic trick of knowing the kanji already to help me learn them quickly.
Of course, depending on how much you already know, it might be more doable for you than it was for me! But if you’re planning on doing WaniKani at the same time, that’s a lot of SRS. You might want to consider only adding especially common words, or words that contain kanji you already know, or use some other criteria to help you limit the number of new cards you’re adding so you don’t get overwhelmed.
that sounds reasonable, thank you for this suggestion! <3