Suggestions for tweaking router?

Just picked up an AX6 router (AC4300) - and I don't really want to go through the 160 page manual page by page..

If there are some router guru's out there, what would you suggest I do (if anything) as to changing the basic settings on my working router. This doesn't have to apply to this exact router, but general info would be helpful to many I think. QoS? Setting channel numbers for 2.4 and 5.8 frequency bands? ... I know I'm missing a lot and your advise would be helpful.

Thanks
Scott