Conceed a retreat to the mainland of Italy. Build up the cities there and keep two stacks at the top. You will be able to afford about 4-5 when you have maxed out the main Italian peninsula of its wealth. You should be able to max out two mines. The reason for two stacks is that they can take a bashing and give one to defend and after a few years of that your two stacks will be coming close to Gold Shevrons.

These stacks will then be really useful for the Greece push. Just get into a habit of retreating and rearming them in Italy on a continual basis and also utilising and strengthing any new generals/family members to lead them.