"I'm still learning but what a glorious sound when it works."

That's why a melodeon.

Right there.

There's a quote from one of the greatest English style
melodeon players, living or dead. Yes, our own Martin,
in case you didn't know.

And HE's still learning.

That's why we love the melodeon.

I guess really devoted guitar players find the same thing, but
for Martin, and yours truly, it's the silly, simple button box
that makes us feel that way.

Regarding song accompaniment, have a listen to his work
backing Waterson-Carthy (and I believe Eliza C. as well)
on any of a number of albums. Damned clever job of keeping
up with the various modalities and thirds-less ambiguities
of Martin C's arrangements.

I picked up the melodeon a couple of decades ago, being forced
to be "authentic" by a Dickens Faire event. No piano accordions
allowed.

Now, I can and do play piano, piano accordion (not any more),
English and Anglo concertinas, guitar, and banjo. But nothing,
absolutely nothing, has taken me like English melodeon, both
for song accompaniment and for tunes.

DO learn to cross rows as quickly as possible, and DO acquire
an instrument where the "crossed" row is as suitable to your
voice as possible in major and minor keys. So, if you like to
sing in D major and in E-minor, you want D/G. If you're happier
in G-major and A-minor, then you want a G/C. A/D/G three row
is a bit heavier, but gives you those three keys plus Bm and
Em conveniently. G/C/F gives you those plus Am and Dm.

Some folks, some of whom are even very popular and oft-recorded
never progress beyond pumping and droning away on three-button
chords.

Please don't be one of those.

Learning to play tunes on the box is a step towards learning
to play lyrical, violin-like accompaniments, something for which
you will be loved and admired.

Do not buy an absolute piece of junk--- a Hohner "Pokerwork"
(not the Chinese version) is the absolute minimum, and even at
that you should go to a quality supplier such as the Button
Box if you're in the US and have them do a tuning and "action
job" on it before delivery. You don't want an instrument with
a flat keyboard where the button plunges deeply into the abyss
when pressed.

Too many people treat the thing like it isn't a "real" musical
instrument.

Others reject it because they've saddled themselves with an
inferior instrument...a really skilled player can get some
serious music out of the 15-dollar Chinese one-row "Parrots"
that are sold as childrens' toys. A new player needs one that
doesn't waste its air (since new players do waste their air).

A new player will have trouble even with a great instrument like
a Castagnari Tommy (or Lilly) because they have relatively low
capacity bellows which require a disciplined approach to air
control. Best to stick with a medium (relative to the number
of reeds) instrument like the aforementioned "Pokerwork" or
an "Erica." Or if you want to get fancy, a Salterelle "Nuage."

I remember when I went from Pokerwork to my Tommy, even though
the reeds use very little air, I had to learn to make use of their
parsimonious nature; until then, my bellows were either stretched
out or slammed shut on occasion. Speaking of which, that air valve
is your friend but if you don't know when to use it you'll find
that by the time you really need it you'll wished you'd have
used it a few bars ago. The air valve must go from a big "gulp"
to a "controlled leak" in order to keep the press:draw ratio
nice and even.