This is why I like unicycling as a hobby. A person never runs out of things to do or accomplish. The only bad part is trying to explain to people why it takes so long to learn something that looks so simple. This is usually solved by letting them try to ride the unicycle. When they can barely stay on it even while using a wall for support they have a new found respect.
Drop your seat down to make it easier to pull out the seat, I dropped my seat way down on my 20" and now that I’m pretty much used to it, everything seat in and seat out is getting better WAY, it’s super easy to pull your seat out when your seat is low. I too am working on my SIF hopping, I can do it, but it doesn’t feel natural yet.
Just like Ali said, practice. Its not something you can spend an hour on and get straight away.
The best way to learn would be to ride exclusively seat out everywhere you can. practice sidehops seat out, even if they are only half the height of your normal hops, it will improve your seat out. One day it will click and feel natural, you probably won’t even notice it happening.
I love to ride natural trials on uneven surfaces because it helps improve your stability seat out. When riding trials I hardly ever sit on the seat.