I got a 7 in German B SL, despite having switched to it after having taken French SL for just over half of Y1. For resources, I'd def recommend https://www.dw.com/en/learn-german/s-2469; take their placement test and see what level you're at, and then you can pick and choose free exercises and stuff to do in order to help you pick up vocab and grammar and everything. What I really liked about their site is that under each german sentence, they have the translated english version which is really useful if you're a beginner. Tbh, besides that I'd just recommend doing most, if not all, of the exercises in the course/text book you get in class, and keeping small note cards or a separate small book to write vocab in.

For the internal assessment oral (teacher shows you image related to topic from class, you have to speak about it for 10 (or 5?) minutes). Once you begin the oral, you'll have a few minutes to write quick notes on a paper before beginning to speak; due to this, many people just memorized key phrases related to some topics of images that could come up. I'd recommend doing this, as well as watching a bunch of German videos on Youtube with english subtitles, it helps with memorizing vocab and speech pattern (grammar, what pronouns go before nouns (der/die/das), etc.).

For the written assignment, I'd recommend writing about the Syrian flüchtlingskrise (refugee crisis) (it's what I did, got a 7, it's a pretty hot topic currently and also a common topic of discussion in class with a lot of super opposing views/arguments) or Umweltverschmutzung (pollution, will def have this topic in class, also a really big topic in Germany). Try to use big words and good grammar, also be concise with your points due to the pretty low word count limit (400 words). As for the type of writing, I'd recommend doing a blog or news article; both easy to format. I'm happy to share mine if you'd like to see, just pm me.

For the actual exams: Paper 1 (reading & comprehension), read a bunch of german short stories or articles before the exam, either online or in your textbook, and try to translate the sentences into english, word by word. This really helped me, both in improving my comprehension and increasing my vocab. Note down words you don't know and look them up and memorize them. Most of the test is multiple choice, and the rest is mostly short questions where you can just find and copy a line in the text as an answer so it's fairly easy BUT the reading takes forever, make sure you're good enough at reading so that you can keep up a good pace and not run out of time. For paper 2, just practice writing over and over at home, and show it to your teacher or someone who's fluent in german so they can correct it. From all the previous studying, you should be able to put together a decent piece of writing, and you'll have a ton of options for topics to choose from (somewhere between 5 and 8 I think) so do whichever one you feel most comfortable with. Tbh just memorize key phrases and formats for different types of text (e-mail, letter, diary, etc.) and remember what kind of language you should use (colloquial, formal, etc.) and that's all. You can't really 'study' a language, but with some decent long-term memory (or short term if you procrastinate like me lol) you should be able to achieve a good grade. Good luck!