hi! I'm also doing Russia for my coursework! I'm doing AQA, so it might be different to what you need to do, make sure to check your spec. For primary sources I've found one propaganda poster (if you google some keywords + propaganda it'll come up), a text published in a book written at the time, and I've got a couple of ideas from my last source so I'm not sure which I'm going to write yet.
I try and outline what the primary source is saying, it's provenance, and then link it to the question, or rather the point its in (how does it link to X, what insight does it provide? Is it overall useful or valuable when looking at said point?)
In terms of overall structure, I'm doing a 100 year period, considering 3 points. So for each point, I try to cover all the 100 years roughly, however if I don't cover a period in one of my points, I try to make sure it's atleast mentioned and then try and include it with more focus it in one of my other points. If I find a primary source in one of the weaker time periods, then that's a bonus too. Anyway, after each point, make a mini judgment linking back to the question, and then of course a final conclusion considering all 3 points at the end.