I have pinched this bit directly from my nice handy Latin dictionary

a - a as in rat
ā - ah as in rather
e - e as in pen
ē - ay as in pay
i - i as in kin
ī - ee as in keen
o - o as in rob
ō - oh as in robe
u - u as in full
ū - oo as in fool

ae - y as in try
au - ow as in town
ei - ayee as in payee
oe - oy as in toy
ui - oo-ee as in Louis (Lewis)
Any other pairs of vowels are pronounced as two separate syllables. Double consonants prolong the sound of the consonant - you say both L's in something like puella, girl: puel-la

b - same as English
bs - ps as in apse
bt - pt as in apt
c - as in car, (never as in ceiling)
ch - as in ochre
g - as in go or gate (never as in giraffe)
h - as in hand but very softly
l - as in let
m - as in man
ng - as in finger (not ginger or ring)
p - as in apt
ph - as in pill
qu - as in quite
r - slightly rolled, as in Scots brae
s - as in sister (never z as in rose)
t - as in stop
th - as in take
u, v - w as in win
x - as in six (ks not gs)
z - as in zero