I really can't cause it takes practice, but I can tell you how I learned.
I watched a TON of (American) cartoons and tryed to copy that art style.
I copied other people's fanart of my favorite cartoons and picked up things from that.
Cartoons that really impacted my art in order:
Steven Universe
Adventure Time
Regular Show
The Amazing World Of Gumball.
Fanart that impacted my art in order:
Lapidot (Steven Universe)
Five nights at Freddy's
Vocaloid (Miku)
Pokemon.
That's it :3