Vowels:
Usually as in Italian or Spanish.
a as in father
i as in machine
u as in spoon
e as in bed
o as in rope
Diphthongs:
ai as in light
ei as in weight
ou as in whoa
Doubled vowels:
When you see a doubled vowels (or a vowel with a macron over it), pronounce it exactly the same as above, just double the length. Compare: okasan, oh-ka-sa-n, with okaasan (or okāsan) , oh-ka-ah-sa-n. To think of it in terms of musical beats, one is 4 beats and one is 5.
Consonants:
Almost entirely similar to English. Two exceptions:
fu – the f in the Japanese fu syllable is somewhat between the English h and f. You don’t use your teeth to make it as we do in English. Try to say “fu” as in “mount fuji” with rounded lips as if blowing out a candle and you will be close to the correct sound.
r – somewhat inbetween an English l and r. When you make the r sound, try to tap the roof of your mouth with your tongue behind your front teeth. If you can make an l sound in Spanish, you already know how to do this (just don’t trill it, or you’ll sound like a Yakuza gangster).
Doubled consonants:
Whenever you see a double consonant, this signifies a glottal stop. Think of the brief pause in the word bookshelf between the k and the s. That’s a glottal stop. For instance, gakkō is read gah-short pause-koh-oh