QUESTIONS (from a starting animator)

https://www.youtube.com/watch?v=6TQtMaxSung <- This is something I refer back to pretty often, I think there's a lot of helpful tips throughout. I am technically not experienced but I am practicing and learning a lot, hence linking back to a lesson from a much more experienced animator. Breaking things down into simpler shapes helps a lot ! Especially for hands. And use reference use reference use reference. so important i had to say it three times. You can even record your own hand movement in the exact way you are imagining it, and then watch it back and work from that. Sorry I don't have much else to say, but this is what has helped me so far :)

also no you can start learning tweening right away, it's an important core concept in animation and you should practice it, no reason to put it off until later

I don't know much about the software you use, but I'm sure that it won't matter for what I'm gonna tell you. When it comes to making smoother animations, I find that key-posing and then drawing inbetween them equally is one of the most important things, I usually start inbetweening at the end and beginning to make sure it's equaly fast throughout the entire motion so it doesn't feel jittery or robotic. Understanding arcs and timing is also a good idea, if you can't afford the animator's bible just watch Alan Becker's tutorial on the 12 principles of animation to get familiar. 

It also might seem like a slap in the face because it did when people told me, but practice really does make a difference. I used to think there was some magic trick to instantly make me better, but I only got better after doing it for awhile. It felt like one day it just clicked for me, so just wait for your click and study the right principles. Good luck, man!