Killer recommendations. Thanks to all.
For background: I have been playing on hard/hard (skipped medium after the Prologue). I noticed that most of my problems with either the Spanish or the Gauls are when I am facing their uber-generals. When it is their stock troops against my stock troops, I have been doing pretty well.

I believe that one of my mistakes is not paying close enough attention to how the AI operates. Another is that I bring very few missle troops to the battle as a rule. (MAYBE one or two units max...)

My standard gig up till now has been to line up the infantry in a long line in the center. Usually with Merc spearmen anchoring the ends. Cavalry evenly split on both flanks, archers in rear and General behind them. I think that I have been making a mistake by sending my cavalry out too early to try and engage their cavalry with the intent of routing them from the field. I think that I need to hold them back to be ready to shore up my weak spots. I also need to work on managing the fire at will function of my hastati. Based on the inputs on this thread, I think that alone will make a big difference.

KPB