Such as, should I start with world history or American? What's a successful approach I should take? Thanks very much for any help.
I think it depends on what you're interested in.
For example, I'm mostly interested in British and Roman history so I started by reading books on those topics before eventually branching out into other parts of the world.
However if you want a general view of world history John Green produced an entertaining series of videos called Crash Course World History
This is probably the best approach to take if you're not interested in a particular time period/ civilization. These videos should give you a brief and entertaining overview of world history without going too in depth.