+1 for Miller Puckette’s book (and Pd) - might be a bit hardcore as an intro. for some, but if you’re technically inclined it’d be a great overview… If the second option is more important, there’s no substitute for messing about starting to get familiar with how different primitive oscillators/filters sound in subtractive synthesis maybe first, then moving on to explore other types from there… (FM for example is less intuitive) …recreating/ researching your favourite sounds from records, synth internals, or just trying to make whatever you’ve dreamt of/heard in your head/twiddling ‘til you find something you like and then trying to work out what makes it sound cool… (‘The Computer Music Tutorial’ is a beast of a book, if you wanted an all-in-one reference: https://mitpress.mit.edu/books/computer-music-tutorial )