I have 2 gallons of elderberry wine on the go. However they're coming
out fairly tart, I picked the berries a touch early I think. Alcohol is
roughly estimated at 13%.

It has a very subtle port undertone, I'd love to bring this out a bit
more. Currently I'm thinking of adding more sugar to max the alcohol
out and sweeten it up a bit. What else could I do to improve the
flavour? Something is screaming vanilla at me, but maybe because I'm
thinking of making pear wine with vanilla and saffron.