Almost every gerundio is regular. The few exceptions are verbs that come from a longer Latin form — and they're some of the most common:

Infinitive	Gerundio	English
fare	facendo	doing, making
bere	bevendo	drinking
dire	dicendo	saying

You'll hear facendo constantly: Cosa stai facendo? — What are you doing? It works from the same stem as faccio; bevendo from bevo; dicendo from dico.

Verbs like andare, venire, uscire, dormire are perfectly regular: andando, venendo, uscendo, dormendo.