Work on your pop. It seems so simple but it's such a huge part of park skiing, especially jumping. If you aren't committing to popping off the lip and bringing your knees up, you're not going to be balanced in the air.
Try taking a few laps and just straight airing jumps to work on giving yourself a good pop right as you reach the end of the lip. Concentrate on forward pressure in your boots and landing with your weight centered over you skis. Once you feel balanced and in control in the air, start bringing you skis up further and begin grabbing. Also, always bring the grab to your hand, never reach.
A lot of people skip this step (I did when I started learning) and it really throws off your progression. Take it one step at a time and before you know it, you'll gain a bunch of confidence and air awareness, making trying new tricks way less intimidating.
As for rails, just keep hitting them and hitting them and hitting them. I wouldn't even focus on spinning out of them until you are completely confident in your ability to slide end to end while keeping your balance and popping off (emphasis on the popping off).
When you get to the end of the rail, really focus on popping high off the rail so when you begin to spin your 270s, 450s, etc, you will have plenty of time to turn your head and spot your landing.
Swaps and spins on will all come with confidence. Give these things time and before you know it you'll be slaying park.