Pocus wrote:I posted a question at the wargamer, but here it will perfectly do too

I'm quite impressed by your performance, how you managed to beat in power the others nations, in a nutshell? Italy is not that powerful, at start at least.
At its simplest, Industry. You have to be cautious not to overdo it and keep a close eye on global shortage goods - usually coal but at times manufactures and chemicals. As a trade policy, as everyone says don't do mercantalist and I think that has paid off as I'm running a balance of payments at +2000 so I can sell excess production.
Beyond that, Italy has a surprisingly large manpower pool post-unification which helps generate a large(ish) army.
In terms of options, I'd recommend anyone to go for the Ottomans first. Its not that you gain that much of real value but its relatively easy prestige, trains up the army and so on. Try to be ready for a moment when Austria is isolated - in my game this happened when Prussia and Britain were at war. Attack when they are on there own. They outnumber you but you can use the terrain, I fought a six month defensive battle in the Dolomites, which wore them down enough to allow combat in the open - by then from the Ottoman wars, I had much better troops and commanders.
My war with Britain was simply to make sure they lost prestige and industrial base.
But I am now gaining around 400 prestige a turn and 340 or so is coming from industry. So it has to be that as the core to any strategy with a secondary power.