I tend to be passive for a long time in Italy, just defending Taras from Roman attacks. Taxeis hoplitai and Samnite spearmen (superior to thureophoroi) are a deadly combo, especially with slingers. Taking Demetrias early on is sound strategy, as it cuts the Makedonian kingdom in two. Before you get to that however you'll need to chew through several stacks. When you have Demetrias/Thessalia, their troops south around Korinth tend to be preoccupied dealing with the independent Greeks, so you'll mainly have to 'worry' about Pella, wich should be easy.
Once you get your finances sorted out and start making money, you should save some money every turn with the goal of building a mine in Pella. Mines make disproportionate amounts of money! If you're still at peace with the KH, proceed to capture Byzantion, where you can build mines too.
The Eleutheroi tend to build up the 2 cities on the north western balkan pretty quickly, so when you'll conquer them you'll get 2 high level barracks with little trouble involved. These will give you acces to Illyrian thureophoroi (good) or even Illyrian Thorakotai (sweet!)
Once you start focussing on the Romani, best be well prepared. They'll send stack after stack at you, both Capua and Roma have huge populations to support their armies.
(side note: it might be an interesting game if you opt to abandon Taras and stay out of Roma's way for a couple of decades, just to let them upgrade to their Polybian army. Your choice.)

Army selection - light (mainly intended for early campaigning in Italy)
1 general
1 mercenary cavalry
6-8 taxeis hoplitai
2-3 peltasts
3-4 Samnite spearmen
2 slingers
2 akontisai (fodder purposes)

Army selection - proper
1 general
2-3 Thessalian cavalry
5-6 Pezhetairoi
1 Chaonic guard (optional. useful in taking cities)
3 peltasts
2 slingers
3-4 Illyrian Thorakotai or Samnite spearmen


In my current Epeiros campaign in 240 I control all of Hellas, the entirety of Thracia, Italy minus the Adeui city to the north and the rebel city in Italy's toe (Croton? Region?) and finally Nikomedia and Sinope. Pontus will soon fall and I'm proceeding to take the rebels in southern Italy, and Sicily after that- bringing me into conflict with my current ally, Carthage.
Best part: I got over 100,000 mnai in cash! I think mines in EB should be downgraded.