Maybe try looking up info from governmental websites first? A lot of countries (not US, cough cough) seem to have fairly straightforward immigration guidelines, so they'd probably write up what types of person they are looking for & the standard procedures
Old Reddit posts could be second
And... depending on the country, for some places it may be better to just DIY, some places having a lawyer might be extra helpful
Immigration-specific groups. Not in a major way like completely shutting down immigration or install a per-country cap or something. Since Australia does skill-based immigration, my understanding is that they are limiting the types of ppl they allow in. I'd love to be proven wrong though, if I'm not right plz correct me