One thing that helps me is to practice chords to a well known song.  One I can play without music so I know where the melody is going.  The best way to play chords is with a chordal instrument..well one better suited...first would be a piano keyboard..  25 keys works fine.   then a guitar or uke. A mandolin would probably be easier for us fiddlers because the notes fall the same and the frets help, and if never played a guitar it takes a bit to be able to chord simple fingering..much less barring.. so wouldnt suggest going that route.

   BUT.. you can always put down the bow put the violin in guitar position and practice chording by using fingers to strum..NO PICK.  just lightly with hand.  Our session leader/group teacher even does this quiet a bit to help if there is a newer rhythm player so she can give some direction on some chords. 

It really helps get your head around progressions and what usually works or what may not work so well by doing this.   putting the bow down helps concentrate on just that without having to worry about bowing.

example

just getting initailly I, IV, V is a good start.   almost all western folk or trad type stuff ..even pop or rock will sound normal playing around with those.  Most of us have that sound deep in our mind from listening to rock or pop..blues..western radio music.. As you get more comfortable with that.. Throw in some 7th chords and some minor chords.   The dimished. augmented and sus. even Maj7th minor7ths chords really can be left out and added down the road.  you have to have that initial triad anyway so best keep simple to start.

if a bass is in a track..depending on what they play it can throw off what you choose so irish works really well to practice with.  simple.. almost never has a bass.  pick a fiddle only track so youre not fighting against a guitar or cello players interpretation of the chords...  maybe download the midi from thesession and slow it down or ideally record yourself playing the melody then play your fiddle to it ..chording in guitar position.  still have to intonate though.  

just ideas..hopefully something to try for those interested.