I've played Aduei till 237bc.
As Aduei you're in the red from the start. Take a few reb cities or/and fight the Arverni. You'll be in the red for a lot of turns, depending on which level you play. Try to get some towns with harbors in the west for some economic growth.
Fighting against a lot rebs is tiresome and a lot of battles are in those horrible dense woods

You'll have to use only Longao inf and Sataroas Bow unit to keep the costs low. Try to andvance in Northern Italy. There are some useful units to train. Then on to the Alps for the towns that produce the celtic phalanx Mori Gaesum are great .