If you're learning Italian, it's useful to learn not just ordinary words, but also the interjections Italian speakers use frequently, especially in informal conversations. They can be used to get someone's attention, to show that you're not sure about something, to give you time to think what you're going to say next, and for many of purposes.
These interjections are often accompanied by gestures, shrugs and other body languages, which you can pick up by watch Italians talking amongst themselves.
Starting a sentence with Beh! shows you're a bit hesitant about saying something, while Mah! indicates that you don't know. Saying Boh! and shrugging shows that you don't know and don't care about something.
If you hurt yourself, the thing to cry in Italian is Aiah! This is equivalaent to Ouch! in English.
Tsh! - a tutting sound or the sound you make sucking through your teeth means No! Not to be confused with the teeth sucking sound that English-speaking mechanics make before telling you that something's going to cost a lot of money.
Be careful with Mmmmm! which doesn't show your appreciation for food or other things, as in English, but indicates that you don't really believe what someone's saying.
Allora is the equivalent of well, so, let's see, as in "So, what are you waiting for?" or "So, what's going on?" or "Well, are you ready yet?".