Officer skill system even with the officer management mod made me quit this run. I want to try different things, but I'm locked into doing it through "balanced/random progression". You know what? I don't even care about the new content at this point. So much time dumped into this run and I haven't even gotten a single useful ship blueprint. And, oh boy, what fun it was trying to farm bounties for a single Legion when I needed 4. Even with console commands, it's mind-numbingly boring and tiresome.
Until there's a mod that allows to edit officers like AI cores and switching smods, and proper dev tools that allow cloning ships and officers, I'm done with Starsector.
It's like the most interesting aspect of this game was made to be as painfully uncomfortable as possible.
Oh, and tech-mining still being yet another useless waste of time FOR ALL THESE YEARS is really great! Also, no "in-game" ship search. As if running around playing casino with black markets if you wanted a specific ship is what everyone has the time to do.
Don't level officers until they have max XP, it will stop saying they gained XP after battle when they hit max XP. Save. Level up your officer, if you don't get the skills you need, reload.
Blueprints are most commonly found on larger ruins and Research Stations. Pirates and the Historian will also "sell" you the locations of blueprints. You can raid a couple of blueprints from faction worlds that have heavy industry, after that it will go into lockdown and it will be some time before you raid for mor blueprints.
Larger worlds and military worlds have better ships for sale. Being on good terms with a faction and having a commission with them will allow you to buy capitals from their military markets. Medium to Very High importance faction contacts will sell Capital ships on occasion. Very High importance pirate contacts will sell every type of capital that has a blueprint. The ships that are recoverable after a bounty are random, saving before the bounty and reloading will allow you to grab what you want, although you may need to fight it a few times.
Tech-Mining is only useful on extensive ruins or vast ruins. Improving Tech-Mining and putting an Alpha Core on Tech-Mining will improve what you find by a large margin. Using the bigger ruins + Improved Alpha Core method, I always at least get a few AI cores, and commonly a colony item. Depending on how many blueprints I've found, I also will occasionally find blueprints.
You can shut down Tech-Mining once the ruins have been comprehensibly combed over multiple times, the odds you'll get anything good from that point on is too low to bother. You can then swap out the industry for something else. As long as you keep the world size 3, besides pirates, other factions shouldn't target it.
Use the codex to find which factions produce which ships. Then use the above to get the ships you want from that faction.
As for mods, console commands can let you custom tailor officers and ships via adding, deleting, giving them XP, giving yourself XP, etc.