I bought a standard D/G Melodeon in early April, fortunately for me (a) it came with instructions -a handbook by Roger Watson (b) I live alone. ( the neighbours suffer much much more when I'm practicing on Tin Whistle) The Dave Mallinson's & the MusikFolk manual each show another manual as well. I'm finding most folktunes in D or G are playable - so long as they don't have 'accidentals' -
Though being a learner I'm still having to work out & write down the notes as 4-push, 3-pull etc .
Have fun, Hilary