I think the main advantage a baritone has over the other sizes is having more of a bass string. If you learn to pluck the D string with your thumb and flick-strum the other 3 with your pointer finger, you can have a nice little bass line to go with some songs.
I play Wicked Game by Chris Isaak this way. The chord progression is B min, A, E, then E again.
For each chord I pluck the bass string once, then strum the others, pluck the bass string twice, then strum the others.
It sounds good if you sing along. You can also look up the tabs on a guitar tab site for the picking parts and they should be pretty accurate for this song cause a baritone is just like a guitar without the two lowest strings.
I also like Creep by Radiohead on a baritone. You can combine thumb plucking the D and G strings with strumming all the strings and it sounds good. You just gotta practice and see what combo you like best. Heard this one played several different ways that sounded good in covers.
Another tip is if you see the chords written but don't know the shape, go to a chordfinder site. I like this one:
http://www.ukulele.nl/chordfinder.php
You can look up chords for different tunings and you can look up more than one way to play each chord.
You can also look up a lot of tabs on guitar sites, you just can't use the 5th and 6th strings. If it is just the first 4 strings, that is what you have with your baritone.
I'm not too great of a player, but I do play baritone some. Hopefully this helps.
