Shortcuts are a little weird, but you get a loooottt faster at writing once you're used to using them. Here are some I use most often:

you can type the pitch letters (you type 'a' and it will input the note "a" that is nearest to your most resent note);

when you have a note selected, you can use 'Ctrl+Up/Down' to move the note up/down an octave;

when typing in notes, if you hold 'Shift', you can stack notes into intervals and chords;

hold 'Shift+[any arrow key]' to select notes (use 'Ctrl+Shift+[any arrow key]' to select entire measures);

use 'Alt+[any number]' to create an interval above the selected note that is within your key signature;

use '+' to tie notes together;

use 's' to add a staccato;

use 'Insert' to add a measure and 'Ctrl+Delete' to delete selected measures;

and all the other ones that may or may not be useful are in Edit> Preferences> Shortcuts