Newbie,,
Congrats on your boat.
The best thing you can do first is to take the online boating course and online exam for your state.
Find every manual you can for your boat systems and read thru them. Almost everything is available online in .pdf format from the manufacturers.
As you read, make note of things that need periodical maint. Many things will surface as needing most of your attention.
Just like a car it comes down to Lube, Fluid, filters, and batteries.
Don't get bogged down with every item the manual explains that needs maint. Keep it simple and remember that the items you use most, will need the most attention.
Open the bilge and all access panels and know what everything is. You don't have to know every detail of how it actually works, but just what you are looking at and basically what it does.
I keep a little ongoing "To Do" list in my wallet. When I'm out there, I try to knock off a few small items.
If you have an Air Conditioning system, then the A/C strainer may need cleaning quite often.
Just tackle one system at a time, and learn how it works, and where to look when it doesn't.
Every time you buy a part, make note of the part number, and where you bought it for next time.
I've learned more here, than in any of the manuals.
Read this forum as much as possible.
Know your weather limitations, and don't let anyone talk you into exceeding them.
Always leave yourself an "Out".
Good luck.
AB