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To achieve better animation, you need to make the object you are animating move less between each frame. The higher framerate you are filming at, the smaller movements you have to animate. It's not always that simple, but for starters you should try making smaller movements.
Do you ever film things live and then copy the footage?
I'm guessing you mean to ask if people ever take all of the pictures and then string them together. Yes, a lot of people do. I've never gotten used to it and wouldn't recommend it, but some people are able to achieve very good animation using this method.
This was filmed in 12fps, is that common?
Yes, 12 is somewhat common. Many times people film at 24fps and take two pictures of some movements, which looks the same as 12fps. This is called "filming on twos". There's also "filming on threes" which would equal 8fps. The amount of pictures taken for each movement varies depending on how precise the animation needs to be.
I think have also seen people using 15fps here.
I animate at 15fps as do a lot of other people. It can definitely look very good and doesn't take too long to animate.
This tutorial is a simple guide on how to get more lifelike animation once you've chosen and are comfortable with a framerate. It looks like you've got pretty good gear so keep practicing and pretty soon I'm sure you'll have something that looks great.
