(Side node: German nouns are always capitalized.)
First letters that are the same or similar, then letters that are different (including vowels). Then letter combinations.
l, m, n: the same
r: similar (linguists would say different, but it doesn't really matter)
b, p, d, t, g, k: the same with the following special rules:
h: as in English, but always as in hand, never silent as in hour (example: Hand - hand is pronounced like "hunt") (Actually there are a lot of words with an h in the middle (e.g. sehen - to see/look/watch, gehen - to go/walk, sahen - (we/they) saw), this h is basically silent and just a seperator of the two vowels. Vowels with an h after them are pronounced long, the h is not pronounced typically (would be really difficult when a consonant is following or it's the last letter of the word) (examples: sieht - sees, geht - goes, sah - (I/he) saw)
f: the same as in English
w: like English v (example: Wasser - water is pronounced like "vusser")
v: usually like f (e.g. Vater - father), sometimes like v (e.g. Vase - vase is pronounced like "vaahzuh")
qu: similar to qu in question, i.e. like "kv". In English there are a couple of words where qu is pronounced like k, for example "unique", this doesn't happen in German (unless the word was adopted from a foreign language, but it's very rare).
x: the same (as e.g. in "fox"), i.e. like "ks"
s (before vowels): soft / voiced like English z (example: Sonne - sun is pronounced approximately like "zonnuh")
s before consonants and in the end of words is pronounced like English s, i.e. unvoiced.
ss is unvoiced like English s.
z (everywhere): like English "ts" (example: Zone - zone is pronounced like "tsonuh")
tz is like a zz, is also pronounced "ts", the vowel before it is short.
c: exists on its own only in foreign words, mostly from English and French. In German words only in the combinations ck, ch, sch, chs (see below) and not in the beginning of words.
j: like English y as in year. Except in words adopted from English and French, e.g. Journal - magazine
y: In words from Greek like German ü (like French u, see below), e.g. Gymnasium - grammar school is pronounced like ghüm-naa-zee-oom.
In words from English and French like in English or French (it's the same in French as in English) (example Baby - baby).
In English, short and long vowels are very different. In German, short vowels are really short versions of the long vowels, except the short vowels are somewhat more closed and the long vowels somewhat more open.
short a: like English short u as in cut.
long a: like short a, just longer and somewhat more "open". Similar to the a in father or like the British say the "a" in "can't".
short e: like English short e as in pet.
long e: similar to the short e, longer and a lot more "open". Similar to ai in fair (without the r).
schwa = unstressed/"unemphasized" e (in the end of words, in suffixes like -e, -en, -er, -el): like English "uh", often (almost) silent altogether when an n or l follows, but not silent when it's the last letter of the word (then like "uh"). -er sounds similar (or even identical) to a long German -a sound in many German dialects.
short i: like English short i as in sit.
long i: like short i, longer and somewhat more "open". Just like English long e, ee, ea in Pete, reed, seat.
short o: like English short o as in pot.
long o: like short o, longer and somewhat more "open". Like English oo in door and floor (without the r after it).
short u: like English short u in put, pull, push, like ou in could.
long u: like short u, longer and somewhat more "open". Like English oo in mood, shoot, like u in rude.
aa, ee, oo: like long a, e, o, not longer or different than normal long a, e, o (There are only few words, i.e. Haar - hair, Meer - sea, Moor - swamp.)
There is no ii, instead we write ie (example: Liebe - love is pronounced like "leebuh") (ie is very common).
There is no uu.
Vowels with h after it are long. (fahren - drive/ride)
Vowels with just one consonant after it are (usually) long. (legen - lay, Ofen - stove) (Exception: -en, -el, -er, -e in the end of words, the e is even shorter than normal short e)
Vowels with a double consonant after it are always short. (offen - open)
Vowels with a combination of two (or, rarely, more) consonants after it are (usually) short. (dürfen, darf - may, (I) may). Some of the most common combinations following short vowels are nk, ng, st, sp, tz and r/l + f/k/b/d/g/m/n.
We don't drop double consonants to one in the end of words, e.g. schwimmen - to swim, schwimm! - (order) swim!
ß: is a kind of ss or sz, pronounced like English s. Exists only after long vowels and diphtongs (so not in the beginning of words)
ä: similar to ai in fair (without the r after it)
ö: like the i in first (without the r after it)
ü: like French u (so relatively close to English "ee")
st, sp: like sht, shp (example: Start - start is pronounced like "shtart", Sport - sport is pronounced like "shport"), but only in the beginning of words / word roots (in the end and middle they are pronounced as in English, i.e. as st and sp)
ch after e, i, ä, ö, ü and consonants: like in Dutch without the t (example: ich - I)
ch after a, o, u: like the Spanish pronounce the J in José or the Scots pronounce the ch in Loch Ness (example: Dach - roof, lachen - laugh)
sch: like English sh (example: Schule - school is pronounced like "shooluh", Schuh - shoe is pronounced just like "shoe")
chs: like cks/ks/x (example: Fuchs - fox, wachsen - grow)
ng: like in English "singing", not like in English "longer", i.e. as nasal "n" without the "g"
nk: like in English "sink", i.e. like nasal n plus k
au: like ou, ow (example: Haus - house is pronounced like "house")
ei: like English long i, like "eye" (examples: Ei - egg, mein - my, dein - your) (very common)
ai: just like German ei (example: Mai - may) (it's rare)
äu: Like oy (example: Häuser - houses)
eu: like eu (example: Leute - people)
ie: long German i, i.e. like English e/ee/ea in Pete, see, sea
ph: like f, just as in English (example: Photo - photo, but it's more commonly spelled Foto today; Philosophie - philosophy)
rh: like r, just as in English
th: like t (example: Rhythmus - rhythm is pronounced like rütmus)
-ig in the end of words: like -ich (soft ch as in "Dutch" without the t, similar to "sh")
-tion: "syon" (example: Nation - nation)
-tial, tiell: "syal", "syell" (example: potentiell - potentially)