Firstly you will never get a 'confirmed' kill. Best you can strive for 'claimed destroyed' but it will be entered as such in your Log.
Balloons are difficult targets at times, sometimes spotters can go boom for No apparent reason.
I think of a soldier in a trench, with a bottle of wine, and a rifle, and he's peeved at the whole stinkin idea of a war. Besides it probably seemed a good idea at the time.
I only reference a designated 'Balloon Mission'. Popping Spotter Gas Bags, while it's fun, Nobody cares but you.
You Wingmen have to SEE you do it. I've found the best way, is with target in sight, while you're closing, repeatedly hit ( R )
Now your witness Must arrive home, AVOID all contact with the enemy.
AVOID Warping ( could lose him)
Keep your fingers crossed, Archie doesn't get him, ditto for all engine failures
I've found that even when doing everything properly, the Best you get is average 1 of 4 Accepted
Stray away from the aformentioned Methods - You can "Kiss the Baby"