I'm cutting some dovetails - jewellery box - and I need them to be
_very_ good. They're about 1/2" deep and wide and I want the narrow
edge of the pins to be just the thickness of a saw kerf.

Any advice on cutting really fine and quite small dovetails, and giving
a good result ?

I normally saw the tails out first, mark the pins form the tails with a
knife, then saw the pins. Here I just don't have the space to do that
though, even with a fine awl. Should I switch to pins-first and
cross-marking, or should I lay both out separately and cut them
separately ?

Timber is English ash, so it's pretty well behaved and easy to work.

Thanks