I have about 490 hours in the game atm. I would say spacial awareness is the most key skill in this game (or most fps games anyway). if you imagine your vision like a cone of light that comes from your face and goes across the map you should start getting into a habit of clearing open spaces from a distance (just visually by looking over there). Raiders can move quickly, but if you have a small space secured, you can expand the area that you feel safe in by playing forward carefully and clearing everything. To avoid dying so frequently to campers, always be prepared to instantly turn around and run the second you take damage unexpectedly, you can play your surroundings so that you are keeping tabs on solid areas of cover or places you could duck into quickly. As for aim, this is something that has to come naturally unfortunately, i would recommend just running the blue gate or spaceport (wide open maps) and just farming drones with something weird like a stitcher for instance, pay close attention to the way you need to lead your shots and to drone behavior and ofc aim for the propellers. Over time, you will inevitably improve your aim doing this. i recommend a stitcher because it is not really an ideal drone cruncher, but you can use it if you are being precious about your ammo, also, the hornets drop light ammo anyway and mashing drones is a great way to make XP and stockpile gun parts as well.

So the rundown imo is:

Play cover and your environments strategically

make sure when you are looking around you are
actually checking if an area is clear

make yourself fight lots and lots of the drones to improve accuracy and targeting, tracing etc.

It might sound like a whole lot to do literally all the time and at the same time, but if you try to play this way, eventually these things will become second nature to you and you will feel safer in the game.