Do not try kings gambit and Halloween gambit. You will lose a piece (like knight)
Books and Opening

I'm not good with books and I'm only familiar with a few opening/books like King's Pawn Opening and Queen's Gambit.
What are some good books/openings I should try? Why?
First, forgive me, my English is too bad to express clearly
I don't actually try to remember the opening/books, I only remember some moves that may be moved often, that's why I do Reti Opening.
Actually, if you're not good with books, you should try as many opening as you can at least 1 time, and find the opening you feel good yourself, that shows more factual than a suggestion.
Dig deeper on what you want, if you really want a suggestion, I'll suggest Reti Opening, for 3 reasons:
1: I love that opening
2: Reti Opening has tons of variations, also includes Queen's pawn opening system, King's pawn opening system (not King's gambit).
3: Although Reti Opening has tons of variations, but you can easily make proper move with opening principle and common opening move.
Dont many Reti's transfer to other openings?, just in a different move order? like it could turn into a two knights caro-khann
Exactly. That's also why I suggest that opening, if you want to train yourself to do better in opening/books, this will be a good choice
For me, Reti Opening is not really hard, because I do every opening when playing daily chess lol.
Besides, if it's easy for your opponent to transfer to other openings, so can you. That's why I love this opening.
I do Van't Krujis Opening because I feel like it is secure and I always win with it.
I also suggest Scandinavian Defense and King Francietto's
Van't Krujis is bad, thats why your 800.
van't krujis is not "bad" in the sense that it loses or gives a large advantage to black immediately.
GM Axel Smith, author of the "woodpecker method" and "Pump up your rating" (I have this book) wrote a book about 1.e3 - "e3 poison".
Is there a digital copy I can look at?
I don't know, you can google them if you want.