I have a %100 Win/draw record with Italy on this website so far, so maybe I can offer some insightful advice. I'll try to be as general as possible so that the advice might be useful to a new player.
First, I think your best natural ally is Germany. That is the country least likely to take an SC that you want for yourself. Of the 18 SCs Germany would likely get for a solo win, very few are ones that Italy typically gets in a solo win scenario. A strong Germany often creates a situation that is good for Italy.
Second, your other good natural ally is Russia. A strong Russia often is good for Italy, but slightly less so than Germany because Russia's 18 usually include all the Turkish home centers and sometimes some of the balkan centers that you will need for yourself.
Third, your worst enemy is Turkey. If Turkey is able to ally Russia or Austria, he will build a bunch of fleets, fleets with no other realistic objective than taking all of your centers. If Turkey DOESN'T build fleets (if he is foolish, persuade him to build just armies) then you should invade him anyways because he won't be able to defend himself, and your 18 centers will typically have to include the Turkish home centers.
Fourth, only attack France at the start if you're CERTAIN that England and Germany will too, AND that Russia will be focused on the south and not pressure England or Germany into making peace with France.
Fifth, if Russia and Turkey both want you to attack Austria in 1901, you probably shouldn't do it. Whenever R/T ally, the best scenario for them is that Italy helps them kill Austria, and then Turkey fights Italy while Russia focuses north while they both take all your gains you got against Austria. I've seen plenty of games where the first player eliminated is Austria and the second eliminated is Italy. If Russia wants is serious about a long term alliance with you, tell him you want to take out Turkey first and Austria second. If he won't attack Turkey, then you probably shouldn't attack Austria.
Sixth, you don't have to grow fast to play a good game. I've seen plenty of games end with Italy included in a draw even though Italy didn't go past 4 centers until 1905 or later.
I've seen many Italian players make stupid, suicidal moves from the strategic point of view because they just wanted to take a center. If Austria is protecting you from R/T, don't take Trieste just because you can and because you haven't taken a 5th center!! You will be next! Don't take Marseilles just because you can - what if the fall of France leads to the English breaking into the med?? Pay close attention to what is happening around you strategically and don't ensure your own defeat by greedily taking centers.
There's a lot more but I'm tired.