The best thing about the Carthies is that you can recruit excellent local troops in each of the main locations you will operate in. Africa, Iberia, Sciliy/Italy and Gaul. I would suggest that you use mostly these local troops as it makes the campaign more interesting and actually they are usually very suited for the area you are in. For example the numidians (archers, skirmishers and cavalary) are all excellent in Africa as they are fast have good stamina and have bonuses fighting in the desert. Personally I wouldnt take many heavy infantry or cavalry into the sand.
In Iberia you want to compete with the lusotannans and have some serious javelin equipped infantry to back up your wannabe hoplites. Due to the terrain and the units at your disposal Iberia is a great place for tactical ambushes and a more flexible fighting style. Iberia is probably the easiest and most lucrative place to conquer after Africa. But IMO Africa must come first.
In Italy you need to go for a Greek approach, and actually the local Greek troops combine well with the Carthaginians themselves. So in this theatre you are likely to have a very solid infantry line of hoplites and phalanxes with some fast javelin armed flankers, decent cavalry and elephants. Yes, make those Romans feel the pain. Elephants are to be kept safe at the back until the lines are engaged and then use them to sneak round the back and cause a chain rout. Theya re the ultimate shock troop.
And yeah, use the mercenaries. You will have a lot of money very quickly as your cities are HUGE early on. So it wont hurt you financially.
Lastly, by the time you go after Iberia, Carthage must have a strong navy. I know its expensive and can be a pain to manage, but you are essentially a martime empire.
Only house rule I would say is essential to stop the campaign becoming very easy is to not use elites at all except one or two units in your principle army. Mercenaries can be of any quality however. Other house rules that I personally used are 1. never put taxes at more than "high". 2. disband mercenary units after they have completed the task they have been hired for (ie the immediate campaign goal has been reached). 3. avoid combat with the ptolemies, its unhistorical, upsets the balance of power in the east, and most importantly - is very boring unless you enjoy phalanx spam. If you can manage to keep decent relations with them you can probably buy that middle east provinceyou need for the victory conditions.
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