Perhaps I was a bit hasty with my recommendation about the vowels, but be careful with how you're sounding out 'giorno' -- because JOR-NOH, to a purely english speaker, will come out a lot differently than how 'giorno' is really supposed to sound. And if you really think about it, that 'I' is crucial to accurate pronunciation.
Sure, it's not as blatant as 'jee-or-noh', but without that "I" you will sound VERY american. I guess you could even argue that anyone breaking a word up so blatantly like 'jee-or-noh' will sound incorrect regardless of whether all the sounds are there or not. But if you actually speak the word at a normal pace, jeeornoh really does start to sound how giorno is supposed to sound.
Anyway, i'm sure we could argue about these minute details for ever, but what i was really trying to stress is that Italian is a lot different from the germanic languages (like german, english, and dutch) that often have silent letters, or letters that do double/triple/etc duty with different sounds.
Italian is very straightforward. If you know what sounds the letters make, more often than not you will be correct if you just sound out a word.
But again, pretty much everything goes out the window when you start talking about dialects!!!