What I've learned after 60 hours of play:
1) The Philip of Macedon campaign is a little misleading as to how this game actually plays. That's because the Macedonian phalangites so out-class everybody else that the campaign is too easy. Admittedly, I haven't played the whole thing and the most difficult challenges probably lay ahead. But if you try playing the Sandbox game or Archidamian (spelling probably incorrect) War campaign the same way, you're in for a rude awakening.
2) Whatever you do, do it with overwhelming force. For my first attempt at taking the Acarnanian cities in the Archidamian War campaign, I loaded up 3 triremes to transport my troops for a quick siege--and was utterly destroyed. Had I Philip's phalangites that plan would have been good enough. It was not even close here. So the next time, I took 7 triemes (6 with hoplites and 1 with peltasts, just because) with another handful of peltasts joining overland from Naupactus. Well, that did the trick. 3 hoplites laid siege while 3 more + the peltasts stood guard against reinforcements. Resulted in a pretty epic battle, a victory this time, learned the hard way.
3) Pelt the enemy with Peltasts. And lots of em. That's a trick I learned from the AI. 1 hoplite bde with 2 supporting peltasts is better than 2 hoplite bdes. 6 peltasts alone is probably better than 1 hoplite.
4) Don't be afraid to disband units, esp when they haven't gained any experience. You need to watch your expenditures. Keep strong garrisons at key points, but that's all.
5) Sometimes you just have to let the enemy do its worst. There are worse things than having a farm burned or a mine captured. Just wait til the baddies are gone and then rebuild. (This is where I wish there was some value besides the material to raiding. Say if there was some kind of factional "prestige" rating that is negatively affected by enemy raids. Maybe the prestige rating would affect diplomacy or troop quality or something. That way, the raids might have an even greater moral impact than a physical one. )
6) I've been playing computer wargames since C64 days (board games before that) and I must say this is one of the most intriguing games I've come across. Hats off to the developers! Looking forward to the Rome game as well as the rest of this one (still a lot more playtime ahead here). Also thanks to everybody who has posted their strategy tips on this board (devs and non-devs alike) as well as to Dustin Rush. Love the videos, my man (although I probably won't watch all 80+ of them!).