There are a few very simple tricks to know how to pronounce most German words.
Mostly, all the letters are pronounced similarly to English, but switch out these:
German "V" is said like an English "F"
"Viessmann" is said "Fiessman"
"Beethoven" is a said "Bait-ohfen"
German "W" is said like an English "V"
"Wien" (Vienna) is said as "Veen" rhymes with "bean"
"Weiss" (white) is said like "vice" (Sadly, many Americans with that surname have lost track of how it is said!
"Ludwig von Beethoven" is a said 'Lood-vig-fon-Bait-ohfen"
German "J" is usually said like an English "Y"
"Johanna" (female name) is said "Yo-hun-ah"
German "ch" when not at the start of a word, is pronounced like an extended hissy 'g' at the back of the throat (ç). Make the sound of air coming out of a faucet instead of water!
"Bach" (stream) is said "Bagggg"
"Ich" (I = first person) is said "igggg"
When "Ch" is at the start of a word, it is more like a "K"
"Christian"(male name) is said "Kristi-yan"
German "Sch" is pronounced like "Sh", don't change the "c" into a "k" like American "Skedule", say it like UK English "Schedule"
"Schule" (school) is said "Shul-uh"
German "S" in the middle of a word is pronounced harder, like "Z"
Eisen (steel) is said "eye-zen"
You may come across the "Eszett" = ß - it is simply a double "S" -> "ss"
Gruß (greeting) is said "grooss"
"Th" is not like the English "the". Just switch in a "T"
Theadore - is said "Tea-a-door"
Ending "e"
English has a special rule that says that if there is an "e" at the end of the word, it is silent and instead, modifies the sound of the vowel in the word, but German does not have that rule, so say an ending "e" as "uh"/"e"
English: "cash" is said "kash"
English: "cache" is said "kaysh" (say the name of the vowel "a")
German: "Schule" (school) say the trailing "e": "Shul-uh"
Vowels ie and ei together
Many German words have these two vowels together and there is a very simple trick to get them right, by saying the 'English name of the second vowel'.
ie - say it as the name of the English letter "E" rhymes with "he"
ei - say it as the name of the English letter "I" rhymes with "eye"
Examples:
Stein (stone) - say St <eye> n (Rhymes with wine)
Wein (wine) - say V <eye> n (Rhymes with wine)
Wien (Vienna) - V "E" n (Rhymes with bean)
Eisenbahn (railway) - Eye-zen-baan.
Einstein (surname) - say "eye-n-st-eye-n" (most people get this name right, in fact all family names ending in "-stein" are pronounced like "-wine")
Spiel (play) is pronounced Schpeel
Umlauts
Umlauts are the two dots over some vowels, (called diaeresis). Just read an umlauted letter as if it was followed by an "e"...
Märklin -> Maerklin "Mare-clean"
Möwe -> "Moev-uh"
Über -> Ueber
Other help
Nouns
All nouns in German are capitalized, not just special nouns.
Vowels
The names of vowels in German is very confusing for English speakers
"A" is called "ah"
"I" is called "E" "E wie Ida" (I as in Ida)
"E" is called "E" but sounds like "A" "E wie in Emil" (E as in Emil)
"O" is called "or"/"awe"
"Y" is called "Ypsilon" (Upsilon)
Spelling
When spelling a word, it is common to drop into the phonetic alphabet mostly made up from common names of people that are unambiguous, just write down the first letter of the stream or words....
Dora Anton Ludwig Emil = Dale
Schule Ulrich Ludwig Theodore Zeppelin = Schultz