Copy default keyframe to first keyframe
One thing I'm really finding cumbersome is when I create a new keyframe, I have to go back and make sure I add an initial keyframe that matches the default keyframe for that property so the keyframe I added doesn't override the default all the way back at the start of the timeline.
An easy way to fix this is to just copy the default timeline's keyframe to the start of the timeline any time we create a keyframe after the start of the timeline.
So if I'm 3 seconds in and I move the hand, a new keyframe with the hand NOT moved would be created at the start of the timeline automatically, as well as the one I created at 3 seconds.
If I wanted to change the default starting position of the hand I could just change it on the default timeline.
(Another thought would be to not override the property until encountering the first keyframe on the timeline but that wouldn't give us a way to set the tween for that keyframe)
When you want to move stuff in a timeline its good to duplicate the "default" instead of creating new timeline
Then all the initial info is on 0:00 in timeline so when you add movement you don't need to remember to add every variable into it
in short:
when you create timeline you need to add all variables (like positions, speed etc.) you want to move/ change manually on start of the timeline
but if you duplicate the "default" its all done for you.
Then you could just delete all the properties you don't touch in the duplicated timeline. That's a good idea!
Looks like not all properties show up on the default timeline if you don't "touch" them when you're putting the characters in their start positions but it's still better than nothing.