I just got my first PS4 platinum with Resogun.
Thought I would share some insight I learned on my way to get the platinum.

Ship Choice: Nemesis will be your go to ship for most of the trophies. Its fast, has homing missiles so you con concentrate on dodging and not worry about aiming, and it has the best boost stat in the game.

Boost: This is by far your best ability. And one of the main reasons Nemesis is amazing. You ignore all damage while boosting, bullets, enemy contact etc. You can also take out a good amount of enemies with this, but I would recommend short bursts used mainly to get out of a big crowd, and then take them out from the side. A long burst is great for clearing the level of ground cannons. Use often!

Overload: I rarely use this. But it can save your life. It takes a long time to charge. When I'm in a bind I go to the boost button. It charges fast and is much more likely to be available when I need it. Overload is better for high score hunt.

Bomb: Pretty obvious, these are a life saver. Use if you have no other way out of a situation. Better to lose a bomb than lose a life.

Trophies: "The True Resogun Starts Here" is the hardest trophy in the game, and in my opinion the one you should go after first. Dive into Veteran very early. The level progression already gives you a good difficulty ramp up. Acis and Ceres on veteran are not that hard and will prepare you more for the later levels than Experienced ever would.

Don't worry too much about the humans on veteran difficulty. The trophy is for defeating the levels, not for high score.
But there is one human each level that gives you an extra life. The bonuses from humans are the same each time you play. Level 5 the 9th human has the extra life. Thats the only one I remember. Sorry.

The last two levels will require a lot of trial and error. Learn the levels and enemies and how to react. The levels are not random. Enemies spawn in order. It might take a lot of tries, but you can do it.

More trophies:
Once you have completed this trophy the others like "1CC" (Complete arcade mode on experienced without losing all your lives) are easy.

Complete a level on Master is a cake walk. Acis on master is easy compared to Mefitis on Veteran

The last tough one is the 15X multiplier. (Unless you were lucky and got it during your first trophy) This is actually easier to get on master difficulty. On veteran your combo goes to 10X pretty fast, and then slows down a lot until 15X. On master the slow down happens at 15X and slows until 20X.

Saving the humans: Do rookie difficulty, or whatever you feel comfortable doing. Mostly self explanatory. Kill the keepers save the humans. Except that some humans do not have keepers. They will just die, or will be released with the light beam coming from your ship. I don't fully understand this, but I have a theory.

I finally got these humans to trigger when I used the Phobos ship, and spammed overload every time it was up. The humans triggered for me when I did this, while they just died when I used Nemesis. I think it has to do with the level of background destruction. Overload takes out a lot of voxels in the background.

Micromanagement: Save 2 humans in 1 second. Grab one human and juggle the other by firing at it. It doesn't hurt it, it just moves. Get him into the teleporter and then immediately get the one you grabbed in as well.

And that is pretty much it. The rest is some easy clean up.

Hope this helps. Any other questions, or things I missed let me know.